Oh, great! Congrats!
The difference between the 6100 and 6200 is pretty insignificant I'd say, so you ended up with a more bang-for-the-buck deal.
Yup, the EX20's 3D is no match for these 2012 Samsung TVs. Crosstalk/ghosting is almost non-existent, and you can actually turn up the depth in movies/games to higher levels than you could with the EX720.
Btw, download Cyberlink PowerDVD ver.12 if you haven't already. It's by far the best player for watching downloaded 3D movies on your PC. Supports practically every video codec out there.
P.S. Something else you need to do - rename the label for the HDMI ports you have connected to your PC and PS3 to 'PC' (not to 'PC1' and 'PC2', just 'PC' for both inputs). Then tell me if you notice any difference.