First, I agree with Zappledan. You might want to wait until you are more familiar with the Kemper and have your workflow, internal rigs, external rig(s) set up. At least see how it fares at more than one practice is my recommendation. I had to phase mine in due to my bandmates insecurity about me introducing new technology but overcoming their fear helped me to learn and iron out things with my workflow and set up before any lives gigs, and that was a good thing.
Second, I don't think what Wheresthedug says is entirely accurate without specific context, but I don't want to imply this is inaccurate either. What I mean is that it really depends on how and what you are using for speakers for the Kemper, what others are using, how the stage is set up and what kind of sound reinforcement (if any) is used, what you are monitoring with, what your band mates are monitoring with, etc.
I have found my basic rig fine for most 'pro/semi-pro' gigs meaning sound man, mic'd amps, etc. (I am still entry level with a Tech 21 Power Engine behind me and an Alto TS210 on the floor in front of me, but in these situations, they work fine for me). For that, I agree with Wheresthedug. However, I am in a bit of a woodshedding hiatus from pro level gigs, and have found that for less professional gigs, (open jams or gigs at venues that do not provide sound reinforcement), it IS different than just having a mic'd amp behind me. In those situations, I have to compete with tube amps and volume creep with no micing or use of the PA to mix the sound, and I have found that sometimes with and without my floor monitor, I do experience a lot of frequency cancellation and suffer from off-axis sound being inadequate. With the monitor, I can at least hear myself, but with just the Tech behind me, unless I start creeping the volume too, it can be challenging.
Until I decide to invest in something more viable, I am going to experiment with bypassing the preamp and running my Kemper into the power amp of my fender blues deluxe - if nothing else, I will have a guitar cab and tube amp I can crank. Not perfect, but it will give me a chance to experiment with running stereo - one channel to the Fender, and one to the Tech 21.