I the bigger the screen the more you will notice the weaker processor...if you want a big TV I'd get a 60-65" plasma. Superior blacks, processor power, and picture quality. Just don't last as long as LCD...3D LCD is even worse...even the 240hz doesn't have enough power to put full HD 3d to both eyes...talk about a headache. HD one eye only. Plasmas are really superior 600hz processor. LCD /led...same thing are playing catch up.
In general yes the plasma is better than the LCD. LCD's have come along way though and the differences are getting negligable. Your 3d statements though are far from truth. I have a 240 hertz sony with active synch glasses. Each eye gets 120 pictures every second. The transmitter synchs to the glasses to flash each eye so they only see the appropriate picture. My 3d is many times better than anything in the theater. It sounds like you may have seen a really messed up demo if only one eye was working.
To the OP glad you got the 240. You won't ever regret it.
Dave