well I have had numerous bicycle, skateboard. snowboard and motorcycle get offs....shattered 2 motorcycle helmets, destroyed a few bike helmets and been through countless skate helmets been to the ER a number of times for other bail related issues, 0 concussions. The thing that helmet research never tells you are the number of helmets that have died the good fight so that your head isn't a shattered pumpkin. I mean seriously are you going to go someplace and report that you didn't get an injury? no you buy a new helmet and move on with your life. One thing for certain a concussion would have been one of a number of "problems" I would have had had I not been wearing a helmet
edit: most hockey helmets are similar to 2 stage skateboard helmets, hard shell lined with soft easily compressed foam....made for repeated impacts of a minor nature....compared to motorcycle, snowboard and bicycle helmets which are designed to protect against a big impact.