There's little doubt in my mind that the GP has better IQ, but I can't use it with the regularity I employ the Contour (a Plus in my case). The form factor of the Contour is so far superior to GoPros package that it is what I use attached to my helmet. I wish the native color was warmer, but other than that, it is much less intrusive as a "riding companion." Also much easier to switch on and off. So for me, it came down to form and user interface, and the Contour is simply a better package for the way I use it. I avoid all the mounting issues (yeah, Contour's accessories are over-priced) by just using the supplied flat mounts on my helmet....so no extra money spent on those to this point.
When GoPro addresses their ungainly form and user interface issues, they will be the leader. Until then, I had to chose between image quality and ease of use, and ease of use won out. I should add that the Contour is not at all bad; just that the color is too cold. I keep it simple, and that's where the Contour has advantages. Blue tooth pairing with I-phone works fine, I could give a rip about the GPS feature, but maybe some people like that, which is another Contour Plus (or +2) benefit. The cold color can be addressed in post, I guess, but it's my biggest gripe.