Just wondering which is better. Personally I will go with plastic since I personally think it is better for shock absorption. If the metal will bent easier, then it maybe offer better protection for the lens. Energy need to go somewhere. Just like cars nowadays, they have crumple zone which absorb energy during impact to deform part of the car while protect the center pod. So if a metal hood is very sturdy, the impact force may transfer to the lens itself and destroy something and that means not much of a protection.