Not tried a Kemper, bit out of my price range. For that mount of dough I would have to spend it on real tubes and iron transformer even if it was a one trick pony.
I have used amp modelling though for the last ten years or so but I know that's not really the same as profiling. I'm currently enjoying Fender Mustang for American sounds and Vox Valvetronix for British sounds. Both have great feel and playability at prices more in line with my budget these days.