It is always bad practise to have a noticeable delay between action and acknowledgement/consequence in ui look and feel. It just causes the user to be uncertain about whether the action was noticed and hence to repeat it.
So how about when the button is pressed changing the display immediately to show the new rig but showing it in reverse i.e. white on black or alternating between black on white and white on black until the actual change has completed?
Yeah - probably a bit too techie/nerdy.
Comes from my background in electrickery 
The Kemper reference manual states the the USB ports are USB 2.0 (FS). They are not specified as charging ports. As such they should be able to provide up to 500mA @5V. The G10 manual states it requires 5V at 1A. So, based on the specs, the Kemper USB port cannot be used to power the G10.
Having said that I have found that the G10 only draws the higher current when it is charging so, for performance, it seems to work fine. But this is not guaranteed because Line6 don't provide a power profile for operation (non-charging).
It seems that the Kemper has some sort of thermal protection for the Vbus (5V) power on the USB because I tried running it with a G10 that had a completely flat battery and the Kemper stopped supplying power. I plugged the G10 in to it's supply and charged it and turned the Kemper off for 5 minutes and back on and when I connected them directly again everything worked and has continued to do so ever since even when topping up the battery on the g10 bug.
I don't think trying to draw more power than the USB spec/Kemper allows for will damage the Kemper - that would be a very poor design - it could cause the unit to break just by plugging in a broken USB flash stick.
I bought the Zoom FP02M - dirt cheap, very sturdy (all metal) construction and works really well once you select the right pedal type.
Also has the benefit of being quite compact.
