ShokWaveRider
Give me a museum and I'll fill it. (Picasso) Give me a forum ...
^ Nice setup. As dumb as it sounds, I would make the recess bigger than the tv you intend to get. I've had to redo my wall twice to accommodate new tv's. It would be rare to find a new tv that fits the recess from the former tv. Aspect ratios change, screen size changes, etc over time.
Next time I will make it as large as I can without compromising on structural integrity. 75" seems to be the going contender. I do not like gaps around the TV though. I also like a picture trim round the hole so if one does not want a TV they can put a picture or mirror up and it would look quite normal.