Was discussing today with a friend via email, talking about tube amps Vs. modellers/profiler.
At one stage, he asked "why looking for a substitute, if you can have the real thing?".
That was more or less a rhetorical question, but I happened to think of what the answer was for me.
I ended up with the following points. I'd like you guys to share other reasons of yours, to check whether I've overlooked or forgotten some important ones.
EDIT: adding here interesting ideas popping up from the thread 
EDIT-2: Just discovered that the post can't be more than 10k characters. So adding a link here
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[Don] The real question should be: if you have the real thing, why would you not dramatically expand your possibilities by simply getting a Profiler?
Sound Quality
I'm most probably within that 99 % of people [re: a statement from my friend] who do not hear a difference with a mic'ed tube amp&cab when the profile is well done.
In most cases, profiling improves the amp performance. A noisy, no-master volume, no-loop amp becomes a modern beast you can tweak far above its design, and with an 80-dB gain knob at your disposal.
Furthermore, this amp will flawlessly interacts with the fx, the EQs and other services (spectacular noise gate, pick attack control, proprietary Kemper compressor...).
The Profiler can sound the way you want it to sound.
Versatility
The Profiler can perform in a variety of ways: direct to mixing desk, with a guitar cab, PA cabs, studio monitors, headphones.
The Profiler alone can suit a variety of different needs and tastes.
[Guitartone] It has to be versatile because guitarists are so different. Ask any pro guitarist (or bedroom player) what his rig was 20 years ago, ask him how many different amps/pedals/rigs he's been through in the last 20 years. With the Kemper you don't have to keep buying different amps/pedals as your tastes change, and you can be 100% sure your tastes will change, what your ears love hearing today they might not love hearing in a years time. No need to trade amps (lose money) to buy the new amp and keep doing the same thing over and over year after year. The Kemper is a GAS killer!!!
[timowens] Being able to make a single channel amp into a multi
channel amp. I have some really nice amps and at this moment the Dirty Shirley is my favorite, it just has the tone that I've been looking for, but it's a
single channel amp which doesn't work so well in a cover band. With the
KPA I have made several profiles and I can switch from clean to crunch
to lead without touching the knobs or trying to balance the sound
levels.
[hollowbuddy] Creating not existing amps !!! You take a profile of one appreciated amp and tweak a lot the
amp/cab/eq parameters to your direction then play with the different
cabs and you get a "personal amp", ready for your own use !!!
Consistency
The Profiler doesn't change its sound depending on the tubes state, the mains quality, the phases of the moon and other accidents X)
[Don] You can take on stage the same exact sound you used in your record.
[guenterhaas] On every show I have exactly the same sound direct to desk. I heard so many bands with horrible guitar-sounds, even when they have the nicest amps on stage, very often it's hard to mike guitar-cabs on stage and they can destroy a lot of the FOH-sound.
Plus, the FOH-guy loves me..... no loud guitar-signals on stage creeping into all mikes, much better FOH-sound.
Economy
Being short of money, I would not be able to own more than one high-quality amp. For the cost of only one amp I can play hundreds of them. Not to mention the several different profiled cabs.
I can also have access to amps I would never be able to buy, such as custom amps, custom modded amps, rare or unique amps...
I will have access to most of the amps which will be designed in the future.
I will save the amps' maintenance costs (tubes, repairing).
Practicality
The more expensive, rare or... heavy your amp(s), the harder to move, transport, take them at gigs or rehearsals.
I can profile any great amp or pedal combination (within what can be profiled of course) I came across at friends', gigs, rehearsals.
I can use the Profiler with many different instruments, included basses, acoustic guitars and anything amplified via a pick up.
You can go abroad with just your guitar, find/rent a Profiler, remotely access your 5,000 profiles and have your sound all over the world.
If there's no Internet connection, you can always rely on your USB sticks (3 of them, 2 of which for backup purposes)/HD/tablet/smartphone.
[guenterhaas] I have recently been on a big tour (60 shows) with KPA, midi-floorboard and a few guitars. I could play all kind of electric (strat, Les Paul, ES-335) and acoustic guitars (steel- and nylon-string) with the KPA. For me a "normal" setup would be at least one multi-channel-tube-amp (f.e. Diezel VH4), 2 miked cabs for stereo, an effect-rack + midi-footcontroller, some stomp boxes + a different setup for the acoustic guitars.... that's a lot of equipment (don't even think about having everything twice for spare...).
Playing
I can use a cracked amp an low or no volume, and/or use headphones and silently play at any hour of the day.
Services
I can have lots of fx and be sure that there will be more available in the future to choose from w/o the hassle of assembling a pedalboard, carrying its weight and real estate around, having to do with (several and different) power suppliers/batteries, hum & assorted noise, cables... and when you get a new pedal you have to rethink you perdalboard... and so on.
The Profiler is always evolving: in 10 years, it will have had tens of free upgrades, updates, amps, fx, functions...
Stage
When on stage, I can feed the board with a much more consistent, robust and clean signal than with a mic'ed amp.
I can keep the stage noise level low, monitoring is much easier.
[Alex] You can adjust the monitor volume leaving the FOH volume unchanged.
Studio
Recording is waaay much easier than choosing the mic(s), placing them, finding the settings...
It's much easier to get a professional sound than with amps, mics, mic pres, placements...
[db9091] I can get a professional setup without having the great ears of a studio engineer, and get much closer to a professional result than recording amps on my own. A huge boost for the hobbyists, but a boon for the starting-out professional.
If I want to redo a track in the future all the settings will be stored and recallable with a single click (w/o having to remember which mic you used, where you placed it, how was the mic preamp set and so on... provided you still own that mic and pre).
[Andy] On average, if I record a full band, I'm to setup mics, equipment, room mics, levels, unity, phase, EQ, compressors etc. This is all before tracking, on X amount of amps... normally for recording, I use 2 or 3 (per person) and for bass DI + Amp - that's a lot of work, and can easy eat a day just in prep.
The Kemper, in takes seconds to find the profiles for the session. and because I have 4 Kempers I can track 2 people (in dual amp mode) at the same time. without all the noise (if I wish).
Cost: this brings down artist/label costs, as they don't need to pay for a day prep, this means they can get creative for longer, or simply pay for less time, or better still use the extra time to add extra parts, experiment, have fun.
Security, If they want to use real amps, then I take profiles of all the setup directly after tracking. an exact replica of what was tracked
(but not mixed) - this means if any corrections needs to be done, then its easy as pressing a button and re-recording with no differences (this always gets the jaws to the floor, love that moment).
Being into audio, and anal about what I do as a perfectionist, the
Kemper allows complete control (with direct, not room) of your prep
stage still, so you can still add your trademark signature if you wish.
and that is far more satisfying than, "hey I made this preset out of
turning a few knobs from an already existing amp simulation".
I can effortlessly reamp my tracks remaining in the digital realm.
[Don] Franz Plasa - and this man owns some very cool and unique vintage amps - said that the Profiler is enabling him for the first time to record two tracks of these incredibly rare amps simultaneously with slightly different settings.
You can't just buy another - let's say Bassman - and put it next to the vintage one, and even if you were able to find one with the same specs and could afford the price tag, it still wouldn't sound the same.
[nightlight] The luxury of choice. You can fit into practically any recording session with a Kemper. There are thousands of profiles and with the rig librarian, it's easy to find something that would sit in almost any mix or jam session. And the number of profiles are growing.
Musical culture/Experience
It has happened that Kemper users have bought an amp after hearing a profile based on it.
[Don] It's a great tool to get to know new gear. I bought mics and speakers based on profiles I liked that used these and was not in the least disappointed.
