I'm not sure where you got your input lags from but the GT50 input lag aren't 42-50ms they are 24-30ms in game mode. I game all the time and It doesn't even have to be in game mode. I can game in Custom anytime. You can't compare a low end model with a higher end in pic quality either.
Here you can educate yourself:
In most of our recent TV reviews we’ve been using our new LagTest device to get you gamers a more accurate handle on input lag figures and here it threw up its first surprise result. We found the GT50 to lag by around 45 milliseconds, which is higher than previously thought, and just goes to show the inconsistencies and pitfalls of using the camera method. In this reviewers eyes (or should that be hands) a number like this is fairly easy to adjust to for most single player games but competitive gamers might well not be satisfied and, again, we’d urge a demo if gaming use is of major importance to you."
That's with the Leo Bodnar device, which is much more accurate. And remember that tested tv was 42 inches, If you have the 50 inch or bigger it likely has more lag. The 50 inch S60 scores 34 ms. Which puts it right at 2 frames (you don't want to go any higher than that).
I also suggest you read this guide: http://forums.shoryuken.com/discussion/55593/the-new-definitive-hdtv-lag-faq
"1 frame is approximately 17 milliseconds.
Ideal (unnoticeable) delay for fighting or rhythm games is 8 milliseconds or less, or 1/2 of a frame.
Acceptable (playable) delay is 9 to 34 milliseconds, or 1/2 of a frame to 2 frames. Note that while gameplay will still be affected by a delay of 2 frames, most people will still have a difficult time noticing the difference immediately.
Unacceptable (unplayable) delay is over 34 milliseconds, or anything higher than 2 frames. Typically, this is a point when timing-sensitive gamers will even feel a delay at the menu screen or with the cursor when selecting a character."
Edited by Josam27o7 - 11/24/13 at 10:32pm