To the Plasma fans:
When people say "I am worried about IR", that doesn't necessarily mean that they are worried about burn in. Some people just really don't like IR, because even though it goes away, it will literally cause artifacts that last a couple minutes. That's really annoying to some people, including myself.
Since I primarily use my TV as basically a PC display, it's especially more worrisome. If I were to load up some art-rich gorgeous game, I don't want to be looking at Chrome tabs on the top and a start button on the bottom.
Just some subjective perspective for you.
IR on my 6 year old plasma is nonexistent. The only time I might see a shadow of a previous scene is when I'm turning the channel, on the black screen. But then the new picture refreshes it.