Chris Schulwrote a review of GoPro Suction Cup Mount on July 7, 2011
I stuck it on my motorcycle last week. It ended up being a very bumpy ride. A lot of potholes, old frost heaves, cracks in the road. No issues at all. I wasn't completely confident with it and created a leash for the mount, but never had to use it. Mind you, the surface was on one of my hardcase saddle bags. The surface of the bag isn't completely smooth either. It is a bit rough.
Update: I had this on my motorcycle for over 2500 miles from Boston up to Nova Scotia and around Nova Scotia. It never fell off.