I got the Khumbu for free with my rewards point at another outdoor retailer, so that is really the only reason I own it. It is lighter than the Denali, and cheaper as well. I wore it boarding in NC under a venture jacket this winter, when it wasn't quite cold enough for a fully insulated snow jacket. It worked great. It is also surprisingly warm by itself, with only a t-shirt or long sleeve thermal underneath. Although it works best between 40F-55F, I've worn it with a long sleeve shirt underneath down to 30F and been ok. It works great as long as the wind isn't blowing hard, obviously since it isn't made to be a wind barrier.
All in all, I'm 6'1 and 175lbs. and I wear a medium (in everything from TNF), however if you like a slightly baggier fit, you may want to go with a large.