I have the Pioneer Elite Pro-1130HD, and have had it for about 4 years. I never watch tv. Rarely watch movies. Have shown a slideshow from my computer three times, which lasted no longer than 30 minutes each time.
As of a month ago, I have 2 stripes of DEAD PIXELS, each about 3" wide, and starting in the middle going down to the end of the screen, with the other about 6" to the right of it.
I have two other plasmas, both Pioneer, both about 4 years old as well, and one of them is starting to show a white cloud like area at the top center. The other is still fine... *knock on wood*