I was of the impression that the new energy star rated Panasonic Plasma's were very similar LCD's of the same size and while LCD consumption is fixed, the requirements of a plasma vary with the type of scenes portrayed.
Go as big as you can. We sit 14 ft away from a 61" and my wife even says we should have got the 70" RPTV.
If you are limited to 50", I would do more research on Plasma and LCD, also if you are in a recessed space be sure to check what the suggested clearances are, as RPTV's generally require 3-4 inches of clearance to allow for adequate ventilation and cooling of the bulb.
I own a JVC RPTV, but really prefer the pic and lack of motion blurring of plasma vs. LCD...but thats only because I watch a lot of sports programming.
