Yeah the bike is a medium and i am 5'11ish, and i also rented a medium 2011 team dh last year at whistler and it seemed to be the right size! Might pull the trigger on this bike this week if i get a chance. Pretty sure i wont find a much better deal anytime soon.
The 2011 Norco DH bike is a legit bike. Norco have a new frame design this year (the Aurum) so the perceived value has probably dropped a little, hence blow out sale prices. That's my hunch anyway.
It's a good price and I think it's in line with what you're looking for. It's a solid bike, good geometry, functional components, FSR linkage so the suspension works well. Not much bling in terms of spec but for a few days in the bike parks in the summer that is of little consequence. If you want something lighter and/or a bit more top shelf you'll need to look at used bikes to stay in budget.