Disagree Scotty (respectfully, or course). I checked everyone online, esp. other biking forums, and it's about half and half...many put it right to the battery, such as this one...
http://www.pashnit.com/forum/showthread.php?t=17501
This thread has some good information as well:
http://forums.pelicanparts.com/bmw-r1100s-r1200s-tech-forum/517904-gps-hardwire.html
I checked for any and everything that would even remotely relate to a GPS and dangers to hard-wiring and I cannot find anything. I think it really comes down to preference, not safety. If you want to turn off your GPS (or hit the prompt) every time you stop, then go through a fuse, if you want the convenience of keeping it on, then hard-wire it and go. There simply isn't any data regarding fires, frying of the unit, etc...with a direct connect...I've had mine hard-wired since I got the Spyder and haven't had a problem...I've been in 1.5 hour serious thunderstorms with my GPS, and no problems...I do not see a problem with connecting it directly to the battery...I like having it on and whenever I want to turn it off, I remove it anyway...don't want it off while fueling up (don't need to if directly wired)...with a GPS, the most important thing to do is to take the thing with you whenever you leave your ride...never leave it on as you're inviting someone to take it...