So who has one of these, how long have you had it, and how it is holding up?  I fondled one in a climbing shop the other day, they seem really nice and comfortable.  I know it passed all the UIAA tests, but i wonder since it doesn't have a hard shell, how does it take a blow as compared to a hardshell?  I see that it will deform on a blow, and then it will retract to its original shape...which is cool, but what about my head?