I'll throw my experience in here with the IR and pixel orbiter/overscan.
I have a crappy $500 samsung plasma in the bedroom, my wife loves watching investigation discovery but it has a huge ass logo. Because of this I enabled the overscan and pixel shift on it, it basically still left IR (at this point I'm pretty sure its Burn In) but instead of crisp IR is smeared it. Looks like shit. Not too noticeable though during regular content. So I said screw it and turned both options off.
Now in the living room I recently got an ST60. I decided to run lower contrast than normal and still keep pixel orbiter and overscan on. My wife watched investigation discovery for a few hours, and maybe a tad, really hard to see IR would develop but I had to struggle hard to see it even on white screen. So I figured I'm gonna keep my contrast still low (real low) and turn off orbiter and overscan. Wife watched some investigation discovery and I check for IR, crisp as can be it had left the logo. Took a few days to get it to fade (on white screens, normal viewing I couldn't see it). So I enabled both again after that had faded and no real image retention, and if there is its really faint and blurry I can't make it out even on white screens.
So it just depends. My panasonic seems to handle the pixel shift/orbiter better than the samsung in regards to IR and the blurring of it. I have yet to game with a static HUD so that will be quite a test and I fully expect some image retention to be left to some degree.
One little trick that will help a bit I've found that if you alternate between overscan off and overscan on it will change the size and placement of the logo/hud, help not make it stick "as bad". But certain HUDS and logos are so damn big there is not a lot you can do.
For as much pain in the ass it is with image retention issues, the ST60 is by far the best picture I have seen, ESPECIALLY for the price. If I wanted an LED that could get in the same ballpark picture wise I'd be spending 2,800 or more. I just can't justify it. If I could I'd probably go with an LED cause its the set it and forget it with no real worries. But not for twice the price.
Each have their problems, its basically pick your poison. If all I ever did was game though, or at least was a SUPER heavy gamer, I would not get a plasma at all. Unless image retention doesn't bother you. Cause it is still an issue for "most" plasmas in one form or the other.