I'm a recent Kemper owner and I have to say I don't see how anyone could complain about this thing. 5 minutes after taking it out of the box I already had my idea of a perfect tone for recording and about an hour later I had 2 screens worth of favorites that all sound pretty incredible and to me sound exactly like the amp is in the other room blasting into a mic (most of them coming from the Lars Luettege free pack, killer work). I've owned or demo'd just about every software and hardware sim you can think of and the thing I hated about pretty much all of them was the immense amount of tweaking you had to do, especially on the AxFX-II and Bias Amp/FX, to get something decent. With the KPA i just turn it on and flip through a few profiles and done. Little to no tweaking involved and I've never had to do anything other than adjust the gain/EQ.
After having it for about 2 weeks now I admit a lot of the profiles on the Rig Exchange and even by "big names" like SinMix are not my cup of tea, it's hard to say they sound "bad" because to someone else they may sound incredible as guitar tone is highly subjective. I'm too afraid to buy any more profile packs because i always hate to spend money on something I can't test and having to rely on highly polished Youtube demos. My only really complaints are how misleading the EQ knobs are because a simple 0.5 move is either direction is pretty extreme on the sound, the gain on most of the stock profiles is way too high as well but these are simple 30 second fixes, and even with the recent OS update and Rig Manager my KPA will stop communicating with the Rig Manager if i cycle through profiles too fast.
Here is my favorite, the EVH Red Channel through a "Hi Sue" cab (Hesu 4x12?)