Picked up an XB65X900A yesterday from Best Buy. Took them up on the deal if you sign up for their credit card, so will get another 10% back in credits eventually. I think that makes it a great price for the set. Mine was made in May 2014 (Mexico). I updated firmware on it to the latest with no issues. Don't have a full system setup on it yet, but so far, impressed with the image quality. There is some uniformity anomalies, but I've seen that on every LCD I've ever owned.
The sales guy was saying that the late production X900A would support the streaming HVEC codec "per Sony tech support..." Not holding my breath, as we all know the reliability of retail sales knowledge, but it would be a nice surprise if it could.
I'm really impressed with the sound actually. It's probably the only flat panel I've seen that had truly usable sound out of the box. So much so, I'm considering going back for an XBR55X900 for the living room, where I'd like to set up a second set with minimal equipment on the wall. Having good sound support in the unit would be more valuable there than in the TV room.
So far, I have say, bang for the buck wise, this was a good deal.
I really like the X900B. I think it has a bit more pop and the flesh-tones seem a little better. The insanely expensive $$$ X950 is the bomb though. That set has it going on, hands-down. Iffin' I could justify that kind of money, I'd totally buy one.