go the radcam. ive got a gopro, sound is crap. wind noise is REALLY bad and it takes pretty average video in low light and is almost useless at night (eg drift pracs). also if you get the bluetooth card thingo for the contour you can use your smartphone as a remote screen and controller so not really worth getting the drift hd if the screen is the only extra
also i wouldnt trust the suction mounts on any of them, i always add some race tape for extra piece of mind.