I've never heard of the helmet integrity issue. Doesn't seem plausible with a sturdy commuter-grade helmet.
The way I think about safety equipment is that the most effective kind is the one that you always have with you, that doesn't run out of batteries.
Maybe the idea of having a mirror near your face is a concern, but hey, you're already in a bicycle crash, it's not going to be great either way. Wear some safety glasses for the flying debris. The best plan is to prevent that situation in the first place.
* "The strap and/or adhesive mounts could damage the helmet, especially if they’re installed less than perfectly."
* "the larger problem is the camera itself. A helmet is designed to have a surface without protrusions, and a camera represents a significant one. / ... "Anytime you add an external component to a helmet, you can change the performance of that helmet," says [Ian] Hall, [Consumer Product Safety Commission engineer]. "A helmet-mounted camera may become a projectile if it detaches in a crash, but a camera that remains attached could focus the forces applied to the rider’s head, increasing the risk of injury."
And from a Specialized helmet owner's manual: "Do not attach anything to your helmet, including mirrors or lights."
The way I think about safety equipment is that the most effective kind is the one that you always have with you, that doesn't run out of batteries.
Maybe the idea of having a mirror near your face is a concern, but hey, you're already in a bicycle crash, it's not going to be great either way. Wear some safety glasses for the flying debris. The best plan is to prevent that situation in the first place.