This helmet saved my life, no question I would be dead. This is direct impact with the road at 52 mph, coming down the fastest section of Independence Pass in Aspen (no joke; witnesses saw me hit directly on my right-side forehead in the first bounce). Comparing the damaged side with the other clean side, the foam compressed about 60-70% before the entire shell failed. I've been wearing Giro helmets for at least 15 years and am now shopping for a new one. My take on the 3 Giro's: it's worth mentioning that the Aeon is substantially thicker at the front and a bit thicker at the forehead sides, so I assume it would take even MORE compression before it would collapse. Looks larger and a little more mushroom head effect because of the added material - but its also a bit lighter. The Prolight is sized very differently; a medium Prolight fits tighter than a SMALL in any of their other models. All of them are great, but for me I'm getting another Atmos because it has much better venting than a Prolight and is noticeably smaller, more compact profile than the new Aeon.