GoPro cameras mounted to helmets. As a skydiver I own one just like everyone else. Compromising helmet integrity? Not with the stick on mounts
Sure, but a glancing blow the mount will snap, albeit with a potential twist or snap motion to the wearers neck,
But if the impact to the helmet is at 90 degrees the mount, it translates all the energy to the 2sq cm small surface area of the mount. (assuming the impact is not with a pointy object)
Also there is the increased risk of the protrusion fouling cables and restricting emergency egress.
Whilst these circumstances are highly unlikely to occur we should move toward integrated and certificated mounts like those for night vision kit.
Apart from heavy cameras used by skydivers, I don't know of any cases where helmet mounted cameras have adversely affected the wearer.
I developed the first ever TV "hat cam" in 1985, they have come a long way since then!
Mickjoebill