A helmet will protect you from concussion due to a puck, or even a stick, hitting your helmet. I’ve had a slap shot bounce off my helmet, and barely noticed it. Without the helmet I would have sustained a nasty head wound and possibly brain damage. I’ve also gone into the boards, and my helmet has protected my head from concussion. What you perhaps mean is that a major cause of concussion is due to the deceleration associated with the head coming to a sudden stop, as seen often in contact hockey, but rarely in the hockey I participate in. I am sure we can agree that a helmet will not prevent concussion in such circumstances, but I don’t think you have scientific data to prove that a helmet cannot mitigate concussion ie reduce the severity. And neither do I, but I suspect it can reduce the deceleration, and absorb some of the shock waves from the impact. I suspect brain damage can result from shock waves moving through the brain.
For my part I know from experience that the Reakt 200 is more protective than the 4500. Maybe not always, but enough to know that I won’t wear a 4500 again.
Don’t Bauer argue with the VT results, and say that they perform their own rigorous testing?
Sadly, a lot of this thread is “I think that” rather than “Studies show that ... “. You’d think governments would sponsor such testing on public health grounds.