I've never ever come close to nicking the ol' noggin', even in all the crazy shiiit that I've done in my life.
Not saying that couldn't ever happen to me.
If I was in need of a new helmet, I'd take a long hard look at Kali helmets.
It appears that Kali don't sit on their laurels, and nearly every year they come out with yet a better shock-absorbing structure.
Their Shiva 2.0 with their nano-tube tech (1050 g) is about 61% heavier than my current helmet (Charly no limits - 650 g), which is a big leap in weight when prone for hours, but JDietch has a fix for that, or merely work-out more with some good neck exercises, or both.
I like my Charly... it's super comfy on my head, and reasonably light weight, and it has a retractable wind shield/visor for the cold conditions. But some will wince at the thought of wearing a Charly or their clones, believing that they are barely adequate, or not even so.
I purchased the No Limits because the jaw protection was noticeably stiffer than the Charly Insider, plus the added bonus of the visor which I haven't had the need for, yet.
Kali stuff would be an iffy sell for me because of the extra weight and neck strain, but I'd likely wear one if it was a good active day. I know I would have to rig some sort of noggin suspender system, though.