I have 2 guitars that are in Drop C, one in Open G, and it works just fine. If you've been playing for that long, your ear should get you in the general range, then the LEDs help you dial it in more precisely. If you eventually decide to get a KPA, give it a shot, it's a sufficient tool.
I like to silent tune (mute) on stage, we switch between standard tuning in D and drop C in a set. Maybe its a non issue, but i still think they should have put the on/off on a separate swith to avoid accidental off switching, to me it seems like someone was sleeping when they made that decision.
They(Kemper) sure have developed a great preamp though when it comes to the amp sounds, what makes me wait before i possibly get one is that there seems to be much left to do in the firmware development, more effects among other things.
I still get very good results with my Boss GT-pro, but there is no question which amp wins when it comes to amp sounds and direct recording, but the Boss win hands down when it comes to effect versatility and control, it has vitually all Boss pedal effects ever made and with a ridiculous amount of CC control (500 different parameters !). Im hoping Kemper at least gets close to something like that in future firmwares. I also have owned the Boss since it came out and it has been rock solid, never a glitch or anything and that is impressive for such an advanced product that hasnt even been upgraded ( i think just one firmware update has been released).