I rode with one last season and it protected my head during the worst fall of the last 5 years experienced on the last day of operations at Stevens.
I'll save the details but let's say that the hit was hard enough for me to go to the doctor and make sure I didn't have a concussion.
Turns out I didn't and the doctor said that it was my helmet that saved me from a very, very bad outcome.
The helmet wasn't compromised and is still in use this season. Love it.