Jinx i have the M8 40" and it is fantastic, the most impressive thing is no burn in for me at all, i leave games on for hours at a time sometimes, and i do not notice any problem whatsoever, my friend has a Panasonic and within an hour of playing you could see burning, fortunatly it went away the next day but surely it cant be good.
If you cannot afford the F8 u will not be disappointed with the M8