The cameras I use on my cycling and motorcycle helmets are small black cylinders.
The one on the cycling helmet is on top, and half the people I meet think it is a headlight.
The one on the motorcycle helmet mounts on the righthand side, next to my jaw, and in all probability, no one sees it.
I wouldn't be caught dead with a clunky, box-like GoPro sticking off my helmet.
They are functionally good cameras, but the form-factor suck rocks for helmet use.