From what I’ve heard its much better to mount the camera to your body rather than your bike. The reason is that your body absorbs bumps better so the video will be smoother. In terms of body mounts the chest mounts are smoother then the head mounts because your head bobbles around a little more. Hope that helps.
I used the go pro hero camera on my tour from LA to SF. It worked great. The only bad thing is that it only took SD cards that were 2 gigs or less, and the video mode would drain batteries quickly.
I was surprised that the video wasn’t too bumpy when I had it mounted on my handlebars. I used the chest mount a couple of times, and got some good shots. I didn’t have the helmet mount. When I have time, I’ll try to upload some videos.