Contrary to the popular opinion, GD is not that much more reliable than KS. What makes it "better" is its serviceability; one can fix a broken GD using a drop of chain lube, a screwdriver and sometimes a pair of plyers.
Having said that, my personal experience with GD is rather negative.
First, it's lateral movement is annoying. I have incorrect hips technique, where I am using hips to further pivot the bike. It works well on road bike, but on a MTB it is not the best technique to have. Still, this is the technique I am using, therefore lateral movement is a big downer.
Adding insult to an injury, GD breaks down quite a bit. Granted, it is easy to fix, but I would expect a 350 USD product not to require any fixing.