Catrike UK said:With a camera stuck on it, waiting to snag on the road if you come off. ouch!
Not so. My camera actually sits just under my helmet on a head strap!

Although you are correct, if a camera is attached to the helmet, it is possible that it would increase the risk of rotational injury. However, I think the advantages of wearing a camera vastly outweigh the very small risks of wearing it.
Of course I have no statistics to back that up.