The stage is blazing fast to me. It takes about 20 seconds to start up, which is typical for a processor of this caliber (Helix and Fractal FM3 also take this long to start). Patch changes are instant, which is very unusual for processors. In fact, one of the reasons why I sold my Fractal FM3 was because of the lag when changing scenes which are supposed to be fast. I don't think you'd be disappointed with the Stage.
Thanks guys, do you know Josh if it is the same for the Profiler head + remote too? (switching speed etc.) I'm still considering it more than the stage because of its form factor. I really know (after long reads..) how kemper DSP works and how much the code is optimized, but prior to spend around 3k for these things, I would really like to be sure in having the same exact performance and future bottlenecks regardless the head or stage option!