I picked up the LE5400 last night and I am very impressed. I mainly wanted a gaming TV and had other specific requests (headphone jack, able to play .wmv files etc.).
I originally wanted to save some money, so i picked up the Sony KDL-ex500..which ended up being a disaster. The lag was horrible for gaming..it could only play Mpeg-2 files. In game mode the PQ was very poor. I was mislead by the associate that there was a headphone jack..and was thoroughly disappointed when I found out there wasn't.
So I returned that piece of garbage. On a side note, when I went back into BB after days of research on this forum I can say I know a heck of a lot more about what to look for in a TV. Originally I was thinking about a Sharp..but we only carry the LED's up here in Canada and they were way over my budget. I also heard there were motion flow issues and once again, didn't have a headphone jack. Finally I discovered the LE5400 and it fitted every category I wanted.
So I spent the extra 400 and got the LE5400. I find lag is a non-issue for me, even when I'm not in game mode etc. I was a bit worried based on the massive 'input lag' thread that I would never find a TV that would be satisfactory for gaming. But coming from a guy who's been playing FPS' for 10 years (and considers himself to be very good), the LE5400 is fantastic. The PQ is perfect in my opinion. I'm not a huge TV expert, so the other minor things that may be large annoyances to some people really don't bother me.
Someone mentioned flickering issues with their PS3 and the LE5400; I haven't found those problems at all. Blu-ray's look fantastic and with trumotion on and the picture setting on 'vivid', it almost seems a little TOO lifelike. I watched Inglorious Bastards and couldn't believe how real some of the scenes looked. I still need to calibrate the settings so there's some work to do.
Lastly, I gotta say I appreciate this forum so much! I learned everything from input lag down to how to check and make sure you have an IPS panel (which I did in the store).
Black Ops awaits!