As far as impact protection is concerned, I'm curious about how much can really be done by manufacturers with that 1" of helmet between my head and and the pavement, brick wall or Humvee bumper. The extra hundreds can add a little comfort, convenience and I can donate my vig in financing a team at Daytona but what am I getting in protection? A helmet is a really good thing to skid down the road on and at non-race speed I would expect anything but a toy to survive that. My Levi'ed knees and bare elbows did as a kid. Beyond that I really wouldn't expect to survive a helmet breaking crash although it sometime happens. Them's the breaks.
Does anybody really KNOW of anything in that inch that results in a significant difference?