Looking forward to the review! Some things I'm interested in I hope you'll cover:
The larger panel should mean easier reading at the native resolution but I wonder if the edges of the screen might feel to far away when sat on your desk, maybe curved would have worked better.
The increased to 10bit should be a welcome improvement but I wonder if the move to IPS might mean noticeably less black 'blacks' and on such a large screen so close to the face that could get irritating.
Motion! I like me some DOTA2 and CS:GO, I've been impressed with the motion handing of the VA panel, could the IPS equal or improve upon it?
From experience (without testing, yet):
1) The overall experience should be similar to the 40" screen really. If you find that comfortable, I imagine you'd adapt to the extra 2.51" fairly readily.
2) It's unquestionable that contrast will be significantly weaker. However; perceived black depth can be surprisingly good on glossy screens, at least in a moderately well-lit to bright room.
3) It's likely going to be better, unless something is messed up with the overdrive. The BDM4065UC has quirks in its motion performance due to the use of PWM and the fact some pixel responses are extremely slow. It also has interlace pattern artifacts, as I explore in my review. If you don't find any of that bothersome it's highly likely that you'd find the new model just fine. Out of interest, how do you find the motion performance of the BDM4065UC if you set the brightness to '100' (to disable PWM)?