I would give the giant a try because it's a new design which giant has deemed superior to the giant DH, which is still a great downhill bike. I'd also try it because you're going to have a larger pool of parts with the stock parts and your current parts to choose from when finalizing your build. Also it can be fun to be an early adopter, and not to have the same bike as everyone else. The Glory is probably a great bike, and so is the demo, but if you going to get a new bike, why not try a new design?
