Mine sits on the clutch reservoir, within 12" of my garmin and my Passport radar detector with a built-in GPS. It doesn't seem to suffer from or cause interference with either one, but I'm considering a different mounting configuration. Maybe putting it on the tail of the bike, somehow. That would:
1) keep it away from the other GPS's,
2) I wouldn't have to see the distracting flashing LED's at night (I know I could just put a piece of tape over them)
3) give it a completely unobstructed view of the sky, without even a windshield to attenuate the signals.
Another thing I worry about is, if I'm alone and have a serious accident, what if I can't drag myself to the bike to push the "SOS" button? I'm seriously considering buying another one with only the basic service to keep in a secured jacket pocket, inside a small hard case, turned off. That should be pretty good insurance for a total additional investment of $250, then $100/year in the future. Then what if I'm knocked so silly that I can't fish it out of a pocket or remember how to use it? I'll set up a "fail-safe" system, kinda like the boomer submarines use. I'll tell my usual check-in contacts that if they don't see a message from me for a whole day, check my tracker map (they all have a link to it) and send help to the latest recurring location of the bike mounted SPOT, which I always have in tracking mode. I guess I'm a little paranoid.