I do trail riding with some technical elements, and I have decided to upgrade my normal helmet to some sort of a full-face helmet.
I have seen some sturdy-looking helmets, which resemble the motorcycle ones (example). However, their ventilation looks bad, so I don't want these. I am interested in the lighter variant, which looks like a normal helmet with a chin guard attached to it (example) - chin guard may or may not actually be removable.
So, if I get the latter type of helmet, do I get significantly better protection, comparing to non-full-face helmets?
Specifically, will it protect me from a direct face-plant?
Is there a significant risk of the chin guard snapping and hurting me?
Does it matter if the chin guard is made of metal or plastic?