I do theatre shows - and not yet done any "normal" cover band type gigs with my kemper.
I came from using a helix and I do prefer the Kemper. Both in terms of how it sounds and the ease of actually creating those sounds - given I do program every single sound change for the show as an entirely new rig.. so this is actually very important. So far I've pretty much stuck to using the same couple of profiles for everything.. a clean one, a crunchy one and a solo one , with various incarnations of those. I haven't really experimented with lots of different profiles as I just can't be bothered! Although I've kept the helix for certain situations... firstly so I've got a second rig in case I need it, but also because the 'stomp box' mode on helix is very useful for once-off gigs where I don't know what I'll need and just want to run in old fashioned pedal board mode and make everything up on the fly with some tap dancing. This is much more difficult on Kemper and requires "pre-planning". Sometimes I just can't be bothered.
At home I have some basic studio monitors and that's what I use to create my sounds. For rehearsals, I use a QSC K10 , and at the shows themselves I'm completely on headphones. I originally was really nervous about using Kemper for the first time. I found I really had to dial some EQ in the monitor output to get rid of bass and boomy sound, coz without doing so it sounded pretty horrid. However, it only related to that environment and the QSC, and after some EQ'ing I was pretty happy. For the shows themselves, my FOH output EQ is flat with none of those adjustments, and I went and spoke to the audio team after sound checks and they said it sounded fantastic through the PA. They showed me my channel strip on the FOH desk and not only did they not make those same changes for FOH that I did for the QSC, they actually had a bit of a 'smiley face' EQ going on where they had even slightly boosted the bass rather than the pretty dramatic cuts that I had to make. So I learned very quickly to just trust the sounds I'm creating at home.. and not be afraid to tinker with the monitor EQ for rehearsal to get a good sound in that environment. I've now done a couple of shows with Kemper in that way and it's awesome. I've got many compliments on how good I'm sounding.