I think that there's no "I-have-all-features-and-my-sounds-are-the-best-in-the-world"-device. The KPA features a lot of unique stuff like profiling, for me it's also the only digital device with authentic amp-tones.
It is like it is, some wishes may come true, some not. 
It's good that we live in a free world and everybody can have his own taste.
The Steve Vai-clean sounds I know are very "hi-fi", seems that he plugged his guitars directly into d.i. and desk. If you like this sound that's fine, I prefer the clean sounds of old Fender and Vox-amps, f.e. the clean sounds of Jimi Hendrix, Stevie Ray Vaughan, Eric Johnson ect. I'm definitively not into high-gain speed-players and prefer the guitarists with blues-roots, they can be virtuosos, too, but they have a different sound and approach.
There's one Steve Vai-album I really like, it's "Flexable", the album has been produced in the beginning of Vai's Zappa years. The album is very "zappaesque" and astonishingly recorded just with a Fostex 8-track tape-machine. Back then In bought the album (thick vinyl) directly from Steve Vai in L.A. and I also got 2 handwritten letters from him. Of course he is an outstanding guitar-player with a huge fan-base, but albums like "Sex & Religion" ect. are definitively not my cup of tea.
dougc84: of course everything you wrote is right, but I didn't want to go very deep into pedalboards. Like I said the most important cable is the one from the guitar to the input. I'm sure most of us will go directly into the KPA and use the KPA-effects, too. My external effects (Strymons) are connected via KPA-loop and I always go straight into the KPA-input.
Of course capacitance and the length of the cable are very important, no doubt about that. That's why I recommended to use short and high-quality cables in front of the KPA-input (in my case Vovox Sonorus 3m or Spectraflex Fatso Flex 3m). For live-shows I try to avoid cables longer than 5 or 6m and I'm using Klotz and Sommer cables, too.
For pedalboards the Lehle Sunday Driver might be a useful tool.
Netheravon: it's all a matter of taste, I'm talking about "weak" clean sounds and I've never heard a JEM-Ibanez guitar with that huge clean sound from a vintage strat or tele or a very good new model. In fact Steve Vai's clean sounds are the worst I've ever heard.... The neck is very important to get a "fat" tone, if it's too thin it won't work. When it comes to clean and crunch tones, strat, tele, old Epiphone, Gretsch and ES-335 are my favourites.
Just listen to Jimi Hendrix, Jeff Beck, Danny Gatton, Larry Carlton, Robben Ford ect. ect.
Ganz so einfach ist es "leider" nicht, Kemper + Transistor-Endstufe + herkömmliche 4x12" Gitarrenbox ergeben nicht so einfach den gewohnten Sound eines Röhrenamps und den Druck des berühmten "In-the-room"-Sounds.
Die Profiles des KPAs bilden die Aufnahme-Kette eines im Studio mit Mikro abgenommenen Amps + Cab nach. Will man professionell erstellte Profiles wie z.B. von Guido oder MBritt wirklich beurteilen, muss man sie in einem möglichst linearen Raum (ohne allzu grosse Soundverfälschung) mit möglichst linearen Studio-Monitoren oder FRFR-Systemen (Fullrange) wie CLR, Matrix ect. hören.
Wenn Du nur Gitarrenbox und Kopfhörer zur Verfügung hast (beide verfälschen den Sound der Profiles), kannst Du im Prinzip gar nicht beurteilen, wie die Profiles wirklich klingen. Dafür bräuchtest Du wie gesagt -wenn Du den Kemper in erster Linie live spielst- ein FRFR-System. Die meisten prof. Gitarristen spielen den Kemper live mit hochwertigen In Ears (z.B. UE 11 Pro) und haben eine herkömmliche Gitarrenbox nur für den Druck, das Spielgefühl, Feedback etc. auf der Bühne.
Natürlich darfst Du die CabSim nur für die Gitarrenbox ausschalten (Monitor out), wenn Du parallel über die Outputs ins Pult oder ein FRFR-System gehst, muss dort die CabSim eingeschaltet sein, aber das weisst Du bestimmt.
Of course cables are VERY important, but not in all positions. The most important cable is the one from your guitar to the input of the amp/Kemper. You should use a high-quality cable there and if you use pedals in front, the whole chain has to be high-quality, all pedals should have true bypass.
If you use this main instrument cable for studio-sessions and recordings, it's best to keep it short (f.e. 3 m). Mogami, Monster, Spectraflex, Vovox ect. are high-end cables and for this most important cable I wouldn't be too stingy. Anything behind the signal (from Kemper to active monitors/mixing-desk ect.) doesn't have to be high-priced.
I made very good experiences with Sommer cables, they are very good, reliable and not as expensive as the high-priced ones. Klotz and Cordial-cables are very good and not too expensive, too. From the guitar to the input I'm using Spectraflex and Vovox for studio-sessions/recordings, for live-shows and the rest I'm using Klotz and Sommer-cables.
I think it is clear what I meant: to get 74 excellent profiles from an expensive amp-collection of a long-time session player = a lot of good sounds for very little money (= peanuts).
The best JVM 410H I heard so far and these profiles are extremely versatile from crunch to high-gain:
There are many excellent high-gain profiles available, just take a look at the vendors here (Andy/studio monsters, Guido, Sinmix and last but not least the excellent new profiles of Bert).
Bert's profiles sound great with all my guitars, it doesn't matter if it's a single coil (strat, tele) or humbucker guitar (Les Paul, SG, ES-335, Charvel San Dimas), just to make that clear.
I'm not into guitars with EMG-pickups or Ibanez-guitars with ultra-thin necks, for my taste these guitars sound either sterile or very weak (if gain isn't on 11...).
I think it's THE occasion to get Bert's -very expensive- collection of amps for peanuts, it's simply like that.
I wouldn't compare Bert's pack with MBritt or other vendors, it's really something unique and worth to buy anyway. Michael (MBritt) is part of a well-known US-country-band, of course a great guitar-player with his own taste and style. Bert is a session-player, who probably will play a lot more music-styles and use much more different sounds and guitars, there's f.e. a difference.
I don't know Bert and I haven't heard from him before, so there's no reason for me to do any promo for him. He is one of the players, you'll hear all the time, but you don't know personally. I know what I'm talking about, I did about 1500 studio-sessions and more than 20 big venue-tours, but session-players normally are ignored by media, which is fine for me.
As I could see Bert is a member of "The Voice Of Holland"-band and if you're playing there, you must be able to play all styles of music. I'm sure he will use his KPA, too, like I'm doing it for all sessions and tours. I already started to use his profiles on recordings and I didn't have to tweak them at all, they sound marvellous.
Like I said, I like these profiles because they are different, of course there are many excellent profiles on the market, no discussion about that. And I'm really surprised that -after using hundreds of profiles from Andy, Armin, MBritt, Guido, MWagener ect.- I found something new and different.
For me it's very easy: these profiles are an inspiration for my playing, composing and producing, comparing to anything else I bought the amount of money is ridiculously small.
Even for users, who -like myself- already have a lot of excellent profiles, I strongly recommend to buy the pack, especially if you're in anything like blues, jazz, pop, funk, hard-rock, fusion, country ect.
I had the time to sort everything out, made some performances-banks ect., the profiles are outstanding. 
As soon as I have recorded some stuff, I will release it here. I didn't expect to find something like this on the quite saturated profile-market.
Nice solo.
From the very beginning your profiles fit perfectly into a mix and I don't have to make a bass-cut as usually. Very often profiles sound quite impressive alone, but in the mix they can cause problems. Usually you have to handle with undefined bass and "disappearing" mids, when drums (snare !) and other intruments are present. Not with your profiles.
Welcome !!! Bert told me that you build excellent guitars and as I could see on your website for a very reasonable price.
If you start with Bert's pack you start with one of the best packs available, I already bought a lot of profiles from many vendors here and Bert is among the best. My other favourite vendors are Armin (soundside.de), Andy (The Amp Factory), Guido (Guidorist) and MBritt (Michael Britt). Especially good clean KPA-tones are harder to find than crunch or lead ones. To profile a good clean tone seems to be more complex, but there are really good ones already in Bert's pack (Custom Audio CA 3+, Bogner Ecstasy, Fender Showman).
Have fun !!!!
I love the Showman, but the other amps offer amazing clean tones, too (f.e. CAE 3+ and Bogner Ecstacy). The Dick Dale-profile (Showman) is fantastic.
I heard that you build very excellent guitars.
Clutterbilly hits the point, exactly my experience, too.
Bert is definitevely category Nr. 3 and his profiles are some of the best I've ever bought.
sinmix: I don't want to offend you and you know that I bought many profiles from you, too, but I don't use them. Of course they are not bad, many here love them and maybe they are very useful for metal-players. I'm a "Clutterbilly-category-Nr. 3"-guy, too and for my working-field (pop/hard-rock/blues/rock/funk/soul/fusion/dance/lounge/latin ect.) Bert's profiles work perfectly.
It's like everywhere, erveryone has to find his own way, but please be tolerant and not cynical to anybody else.
viabcroce: I've never had a problem with using different guitars on one amp-setting. If I want a strat sound I'll pick a strat, the same with a Les Paul. Of course a Humbucker will have more gain, but that's what I want when I choose to use one. My amp-settings will stay the same, so if I'm using KPA-profiles they will fit for all my guitars. I have to say that I don't use active pickups (except EMGs on my Steinberger GM4-TA) and I also try to find the perfect distance from strings to pickups.
Letztendlich sind die meisten "Tests" im Netz für die Tonne.... Ich habe mehrere Amps hier in meinem Studio (Marshall '70 Plexi, Dr. Z Maz Sen., Fender Blues Junior, THD Univalve, Boogie MkII u.a.) und den direkten Vergleich, erstaunlich, wie nah der KPA an den Original-Amps liegt und selbst für meine sehr geschulten Ohren nicht wahrnehmbar.
Yes, like Bert said CAE 3+ and Bogner Ecstacy will offer that sound. But there is one BIG component also responsible for the sound: the guitar. Frusciante plays -if I understood him right- an original '57 strat with maple neck, using the neck-pickup. These guitars sound very different to other strats, even a vintage strat with rosewood would sound very different (more mids, less brilliance). I own a similar strat ('58 with naple neck, all original) and the sound of the neck-pickup is HUGE, no comparison to my '66 strat with rosewood or my Custom Shop strat '56 reissue with maple neck.
In a direct comparison -original '58 strat with maple neck vs. Custom Shop '56 reissue with maple neck- the '58 strat sounds much, much better. And I have chosen the '56 reissue from about 20 reissues and took the best.
Some of these old strats have a brilliance and punch I've never heard gefore. It's not just the neck pick-up, on many strats the bridge pickup is very weak. Not the '58 one, it sounds very rich with enormous power for solos and leads, very similar to a good tele. Of course there are many weak-sounding vintage strats, too, you have to find the right one.
1) Gitarre stimmen hilft immer.
2) Einen vernünftigen Amp profilen hilft noch mehr.
3) Letztendlich entscheiden die Ohren und ich halte diesen "Test" weder für respräsentativ, noch für besonders detailliert oder gelungen.
Today I had the time to go intensively through all profiles, I didn't have to do much tweaking, just a little bit of eq on some profiles, that's all.
I found everything from sparkly clean tones to very nice crunch- and lead-sounds. The basic character is different from other profiles, with my '58 strat they are "singing" with warm and very nice mids, I love it. My favourite amps are B.E.C. (Bogner Ecstacy Classic), CA3+ (Custom Audio) and Gainland (Van Weelden), simply fantastic.
