I'm new to the forums, and I'm not equipped to test input lag, but I'm happy for my 50pa4500 for gaming. I'm sensitive to input lag as well, and when I first purchased the TV I almost returned because of the mild input lag. Once it's in Game mode there's no noticeable lag.
I have a Toshiba 55L7200u which from what I've read received good input lag results. I can't notice any difference in input between the 50pa4500 and the Toshiba when in game mode(s). 90% of my gaming is done on the LG.
Sorry I couldn't be more help, but since no one replied to your post for a long time I wanted to chime in.