While my fingers are recovering (from almost 24/7 guitar playing since getting a Kemper...) thought I'd finish this thread up with a few reviews of what I ended up buying, hopefully will be helpful to anyone looking for similar sounds.
One comment on paid profiles vs free (i.e. Rig Exchange ones) - while there are definitely gems on RE, it's quite a bit of work sifting these out... plus, while you can generally find a good profile or two of each amp, that's usually about it - whereas commercial rig packs give you a whole range of settings/tones for each amp, which is especially useful if you're using Kemper primarily for recording - makes it much easier to find the right profile for a certain production. And the quality generally is higher... There's a whole art to micing up an amp, and I think this - not just dialling in good amp settings - is where the pros excel. That said, some well regarded profile-makers just didn't do it for me - I guess this is down to both personal taste and pickups - so always find or request some free sample profiles before buying, as it's often hard to tell from audio demos alone. Rig Managers free Rig Packs are also very useful in getting an idea of what's out there of course.
You'll notice I'm mainly sticking to Marshall's & Oranges - these are amps I know well (i.e. the "real life" versions of) so seemed like a good place to start. I have got a number of suggestions from a facebook group re. similar-sounding alternative amps to try out at some point - e.g. Bogner XTC, Splawn etc. - but to be honest I've yet to find any of these boutique amps that (to my ears anyway ) improves on the tone of a Marshall or a Rockerverb (for rock/leads), or a Fender for sparkly-cleans.
Anyway, here's what I've got so far...:
1) Guidorist - Rockerverb - very nice, only a small pack, but ideal for a modern/bold/heavy-rock sound
2) LRS - Rockerverb & Plexi - both great, loads of profiles with tons of different mic/cab combos to cover a lot of tones - e.g. a lot of Rockerverb sounds that aren't covered in Guido's smaller pack. These profiles "feel" great under the fingers, and fit into mixes well.
3) Choptones - Funk Pack - only ten profiles, but all great, nicely set-up effects with these, should cover all my funk rhythm requirements!
5) Nick K - JMP - really nice, retro amp but modern-sounding profiles if that makes sense - I like the way these are set up with rhythm and lead versions of each profile, they don't need much tweaking to be ready to go
4) TAF - 410HJS, JCM800 (from pack 10) & UK Gold pack - all really solid profiles (tons of great stuff in their free packs too) - the UK Gold pack's one of the pricier ones I've bought tho and tbh have slightly mixed feelings - all the amps in it are incredibly dynamic to play and some of the most realistic "feeling" under the fingers - however they're mic'd up very differently to the "single" TAF packs I'd bought previously, with many profiles a bit too dark, and overly "boomy" to my ears - nonetheless, this contains the best "classic rock" Marshall tones I've found so far. It's just that, considering the price, I was disappointed it didn't quite give me all the Marshall sounds I was after, particularly JCM800-wise... however, I managed to fill that gap perfectly when I found:
6) Marco Fanton - JCM 800 - last but not least - finally found my ideal JCM800 lead sound! 10 profiles, all with seemingly very similar (if not identical?) gain settings, but exactly how I'd set an 800 as a platform for the type of Satriani-esque rock/funk leads I naturally gravitate to - lovely profiles on their own, but also perfectly set up to add various dist pedals/effects to give a whole range of lead tones.
Will definitely add to this collection in the future - all the profile makers above have other packs I've got my eyes on, and at some point intend to try out stuff from BHP, Top Jimi, Tone Junkies etc. - but for now I've definitely got all my main bases covered, and my Kemper loaded up with some of the best guitar sounds I've ever heard