I think i may be one of the 2 on this site that actually owns a 42" X5.

I've disussed already about this particular set quite a few times but
in different random threads, but overall for gaming i think many gamers may in fact be satisfyed by the 2 frames/32ms response. However, that's on the wii via component.
Using an HDMI adapter(Scale free & no lag added) there's some 'slightt' lag added in comparison. I tried out my PS3 on it via HDMI with Rayman Origins, Batman : AC and Mega Man 9 and i think it's safe to say that it's slightly over the 32ms range.
For me that personally doesn't cut it.
Try it out and see for yourself. Make sure to do the following for the lowest possible lag
Connect HDMI/Componenet directly into TV.
Turn off Video noise reduction
Turn off Color management - (adds more lag when turned 'on')
Set Color Matrix to 'HD' - (Even if the content is SD setting it to 'SD' causes more lag)
And you're good to go. I've gotta say though, game mode produces one hell of a fine picture picture for gaming. The brightest plasma
i've seen yet, the color gamut is absolutely fantastic, you'll beable to achieve some wonderfuly rich and vibrant colors, the blacks are pretty solid while the motion being pretty good
isn't 'quite' as good as some of the 600hz LG sets, close, but some slight blurring is still evident. But it's miles better than any LED or LCD.
Keep in mind, you wont beable to resolve 1280x720 for PS3/XBOX games considering the 50" plus 42" are both 1024x768. Still looks good though when the shaprness is set properly.
I tend to stick it in 74 for PS3 games. Try it out and see if you like it! I'm going to return mine and go for panny's 50I want to properly resolve 720p for Wii U games, and get 1080p for Bluray, plus i NEED
lower input lag and better blacks which is why the S30 or ST30 for me is a must. You may be pretty impressed by the X3 in the lag department, i'm pretty anal and demanding
however and i need the best. XP"