My biggest personal worry about the gopro isn't that it would fall off in straight and level cruise (really, how likely is it to hit someone?) but that it would fall off after a hard landing. Now I have a camera with footage that can identify me sitting on an active runway. I better park the plane quick and run out there before it gets sucked into the next departing jet.... It would be a real mess at an airport with any traffic at all. That and I figured out there was a good chance the FAA would not be thrilled about any sort of external mount without any paperwork...
Paranoia will destroy ya... You don't have to **** up.