DingoSeanI feel like you'd actually have to add weight to the top while using the GH3 on a 2000... Unless you're using a really big heavy lens and a lot of accessories, but even then the GH3 doesn't weigh a whole lot.
Even if you have to add weight, it's probably better. It'll end up being more stable with more weights on the top and bottom (provided it's balanced).
NMMediaYo Ben try my HD1000 out man. On glidecam's site they also have the weight ratings for each glidecam. Weigh your full setup and see what it says on their website. For instance the 1000 is meant for cameras up to 3.5 pounds. The 2000 is for cameras from 2 to 6 pounds. Make sure you dont buy a bigger one just because though. I see people around rocking huge glidecams talking about how theirs is better because they spent more and in reality they are actually hurting themselves since they cant balance it correctly without enough weight on top.
but if they can balance it correctly with weight on top? then i'm pretty sure the 2000 is the way to go, it's still pretty small too