My ML500 use is about 75% gaming on Xbox 360 and the rest of the time I am watching movies or TV Shows. It's been awesome for gaming so far. I have been playing a lot of Deus Ex which is a very dark game so I have had to make sure my light control is in check but it looks fantastic. I have also been playing lots of arcade games. Super Meat Boy is an XBLA platformer known for its difficulty, so I used it as a benchmark test if:
a) going from a 37" gaming display to 100" would make my performance better or worse
b) if I could feel any input lag
Results are that the change in size seems to have had no effect on my skill and that I can not detect any lag. If there was any significant amount of lag, it should be easily detectable in SMB, however I would still like to perform a real lag test to get the exact number.
On an unrelated note, I am now noticing pretty severe warm-up focus issues, similar to what is described in the Qumi thread. Ever since ceiling mounting it, it is very very blurry when I first turn it on, until it warms up in about 10 minutes. If I focus when I turn it on, it is of course out of focus when it warms up. I am using it in normal mode, not eco.
I am thinking I either didnt notice this at first, because I was frequently adjusting the pj, or this problem is attributed to my apartment being colder than when I first got it. Either way, very annoying