Ouch - hope you feel better.

I can personally vouch for the Specialized Prevail helmet.... earlier this week I did some damage that sound a lot like yours to my helmet, but not to my head... I hit something on my commute - I'm not sure what, it was dark and my light didn't pick it up. It was on a street I'm quite familiar with - only about a block from my house, and I think it was either a small pothole or a small icy spot, but the affect was a rather long slide mostly on the top of my head... I crunched the back of the helmet pretty good. The whole left hand back side was shattered and the retention system was torn out on that side too, but I only had a bit of a headache for about 2 hours and certainly suffered no loss of consciousness. I've never cracked a helmet so dramatically.... I feel quite lucky to be undamaged - other than the headache I only got a tiny raspberry on my left elbow and a few scattered minor bruises. I'm sticking with that helmet. Until now I had some 2nd thoughts about the retention system - it's not as adjustable as all of my previous helmets and I wondered a bit about it, but I'm convinced it works now.