Hmm, thinks I, even though I specifically recommend against doing this on Modern Vespa

Pop! Poof! And smoke pours out of the GPS.
Did you know that mini-USB plugs are 5 volts, not 12? I did. Well, except for while I was doing this, anyway.
The real punchline to this is that I did exactly the same thing five years ago on my Honda Shadow, zapping a Garmin iQue Palm Pilot GPS (which cost a whole lot more)

Since the i2 has been long-discontinued, I was able to find one used for $65, so not too much damage except to my pride. Meanwhile, I've got the Zumo back on, blocking my turn signal and tilt lock lights.