I use the RAM mount for both an iPhone and an iPod Touch on the handlebars (have to have both to integrate phone functions into the J&M system on my bike).
I have had ZERO problems with either after thousands of miles using each. When I got the RAM holder I put the iPod Touch in it and held it over my couch and violently "flung" it back and forth (wanted padding in case it flew out). It held very firm and I knew then they would be secure on the bike, pretty much, no matter what.
I have always had excellent service from them (not affiliated):
http://www.gpscity.com/cell-phone-mount/apple/iphone-3g