Screen burn is my one concern with a plasma considering it will be used for gaming.
It's not a problem. I've played games for hours and hours with static huds. Forza, Colin McRae Rally (that was one of the worst), Gears of War etc etc.
They all burn the screen, and you can see the burn on a solid background, like the Sky guide screens. It only lasts 10 minutes if that, then it's gone.
I couldn't even be bothered running my set in as some of the geeks recommend. I just ran it at sensible levels rather than with the contrast up to 100%.