Wow, those are fantastic. Heh, bet the maker recieved a million e-mails by now
About the on/off setup. I have a couple of sets of these things called Astrojax.
The LED's are turned on an off by way of a key, that pokes in a little hole in the Astrojack, forcing a pin down on a teeny momentary switch that scrolls through that settings solid (constant on), disco (creates a *ahem* tracer effect), then off.
That may be too complicated for inside of the knob, but a set screw would be scary for me. I can just envision myself turning it on or off, and the screw driver slipping to damage (personalize?) my axe. That's my biggest fear, since I've done that in the past.