Great article for discussion. I'm an orthopedic spine surgeon and so thought I might comment on some common misconceptions about Full Face Helmets. I can't find any data that shows they are better or worse at preventing spinal injuries and certainly in my practice I have found most patients with a spinal injury were wearing half shells (granted their are a lot more riders wearing half shells). In the US NICA doesn't allow racing for kids with a full face, but in our league we give exemptions regularly. This rule is in place due to a fear that in the setting of a spinal injury a full face helmet is more dangerous to remove than a half shell. First if you suspect a spinal injury only EMS should be removing the helmet and there are safe ways to do so (including cutting the chin bar off). Second, there is no data on this for mountain biking I can find most people are using old football helmet data. I do see a lot of facial injuries in mountain bikers wearing half shells. I'm not sure full faces prevent concussions better (I've had concussions in both). As far as not looking cool that appears to be regional, we have a lot more folks I see on the trail starting to wearing FF and we all wear glasses. If you are going to wear goggles you better have some serious steeze. What do I do? I wear a TLD stage most of the year and if I am going on anything gnarly. July and August I tend to wear a half shell. Coaching I tend to wear a half shell. I've never had a patient that regretted wearing a FF helmet though, so I should probably just wear one all the time.
PS: I also see a lot of elbow injuries, and I hate scrubbing for surgery with road rash forearm (our trails are cheese graters) so I wear pads (I have sets of Leatt, TLD). Operative elbow fractures tend to have inferior functional outcomes compared to knee fractures.