Yes, I'd look at a GoPro. They are good quality, plus loads of mounts and other accessories available.
None of them have GPS built in, but you can use a separate GPS device to record a track, then combine that with the video afterwards. ie to add overlays for speed or maps etc.
They are a bit heavy and bulky for on a helmet. But you can reduce this a bit, depends on what sort of mount you use. If you don't need it to be waterproof, then the 'Frame' is a lot lighter and slimmer than the standard housing.
Or try some sort of handlebar mount or chest mount.
The new Hero 4 Session looks good. Its a lot smaller and lighter than the other models. Though currently rather expensive, and it seems not quite as good video quality, plus the battery is not replaceable.