It occurs to me that one of the best sprinters in mountain biking is probably Brian Lopes who's like 5'9" and, according to a quick Google search, 352.7 lbs, but that might not be correct. Anyway, I wouldn't put much stock in this idea that there's an ideal body type for downhill and that it's 6'/200lb+. Nico wasn't particularly big and Gwin is pretty average sized. It's not like Danny only loses out to the bigger guys on pedaling tracks. Danny (and everyone else) got smoked by Gwin at Val di Sole, which you can't exactly put down to power.