IR in current generation Plasma is a little bit over hyped, try abusing an LCD/LED panel in the same way and you will get IR no surprises here .....
In most cases you wont find many people around you who have suffered permanent IR with LCD, LED backlit, Plasma or CRT TV, at the most its temporary IR which gets cleared the moment screen gets refreshed. You have to really abuse a set to get permanent IR.
I was in the bandwagon for a flat panel TV recently, Plasma to be honest was not even in my list considering the bad reputation that has been stuck around ... I almost finalized on the ex 710 until i went for the demo on a Panny Plasma. The vivid and bright image on the ex710 sure looked good but didn't suit my taste since the colors were not so natural. The colors on the Plasma were natural and if you like the souped up image quality then even that can be calibrated, and input lag on gaming is nil
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Also please read the user manuals carefully, a lot of people say the warning on IR is put only in Plasma panels , here's and extract from the Samsung user manual for an LED backlit set which i got it from AVS forum sometime back when i was checking on the sets.
The second page of the Samsung User Manual (from their website) for the above LED back-lit TV's has the warning:
Precautions When Displaying a Still Image
A still image may cause permanent damage to the TV screen
* Do not display a still image on the LED panel for more than 2 hours as it can cause screen image retention. This image retention is also known as screen burn. To avoid such image retention, reduce the degree of brightness and contrast of the screen when displaying a still image.
* Watching the LED TV in 4:3 format for a long period of time may leave traces of borders displayed on the left, right and center of the screen caused by the difference of light emission on the screen. Playing a DVD or a game console may cause a similar effect to the screen. Damages caused by the above effect are not covered by the Warranty.
* Displaying still images from Video games and PC for longer than a certain period of time may produce partial after-images. To prevent this effect, reduce the brightness and contrast when displaying still images.