Who here owns/uses a helmet camera i.e. Drift, GoPro, Contour? If not, why?

I'm after one but can't decide between the masses of brands out at the moment, so some user feedback would be good. For me its a balance of image quality and size/weight, needs to be quality enough to actually see whats going on but not feel like having a brick strapped to the side of my head. Option for an external mic also.

Cheers

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