i dont think burn-in is still relevant for plasmas. my wife and kids watch thru Cignal Satellite HD for hours non-stop with the red Cignal HD Logo on top, hanggang ngayon hindi naman namin naaaninag ang after effect nya, for 2 years now.
we've been using ps3 for console games both for a fullhd lcd and a plasma unit for hours, in my case, i haven't seen any significant disadvantage of a plasma for this purpose, that's just for me.
i think im not belong to the "most", since my first unit is a 42" Panny plasma, 2nd one is a 42" Sony full HD LCD, then bought again a 50" fullhd plasma... why? i am not happy with the LCD, plasma serves what im looking for, that's just for me at the very least.