I had the Contour HD1080, which was great, but traded up to the GPS version, which was a big mistake.
There are a lot of people having problems with the video quality on the Contour GPS, just have a look at their forums for more info. Also, the Bluetooth app, which is why I bought the camera in the first place, seems to be causing problems for a lot of people.
Also, the build quality of the Contour GPS doesn’t seem to be as good as the HD1080 and you get a lot of movement on the mounts, which means the video is always a bit wobbly, especially on bumpy trails. The lockable flat surface mounts are the worse. One knock when they’re locked and you immediately get 2-3mm movement in the mount that can’t be fixed.
The goggle mount and the handlebar mount also transmit a lot of vibration to the camera – I think the rail system, being plastic, wears as you use it and the camera then wobbles on the mounts. Okay for skydiving, but not for mountain biking where vibration is an issue.
Contour customer service was okay at first, but when a lot of people started having problems with the GPS unit, especially the video quality, it all went very quiet and people started getting frustrated.
I gave up on it in the end and bought the GoPro HD. Much better mounting options, much better stability on the mounts and the chest mount just works so well for mountain biking. So far I’ve been very happy with it.
If you can get the Contour HD1080 for £162 then that’s quite a bargain, but I still think I’d spend the extra on the GoPro. I picked mine up brand new off eBay for £229.