I don't recall saying the lynx had a stronger bulkhead, but everything I've read about the lynx vs the doo is that the lynx is built to take more abuse.
Skidoo and polaris have both been a bit fragile for a while now, all be it in different ways. Doo has had issues in the bulk head region since the original rev, but hey, they're tunnels don't bend so somehow that's a win over a polaris that bends tunnels but not bulkheads.
As far as an extra 30lbs being so drastic in the mtns, I've yet to see a pro/axys accomplish anything that a doo or cat can't.