dopesun,
My current display is a 60" Pioneer Kuro KRP-600M plasma monitor. I have only two complaints about it:
1) It buzzes.
All plasmas buzz. In fact, almost all displays make some sort of operational noise of some sort. Maybe a fan, maybe a "whine", maybe just power supply hum. My Kuro doesn't really buzz any louder than any of my previous plasmas (a Samsung and an LG), but the Kuro is different in that the buzz actually emanates from the screen itself!
Most other plasmas actually have a second layer of glass over the plasma panel, which blocks the buzz from coming out the front. So with my previous plasmas, the buzz was really only audible out the back and top. With my Kuro, however, the buzz comes right out the front (as well as out the back), so it is much more noticeable and annoying to me.
2) It does show uneven pixel aging.
There are three kinds of "image persistence" with displays.
a) Burn in. This is pretty much a thing of the past and not really something you have to worry about any more. With true burn-in, you will see a "ghost" image on the screen no matter what you are watching and it never goes away no matter what!
b) Image Retention. This is where there is an image on screen, then the scene changes, but a "ghost" of the previous image remains. It looks similar to burn-in, but it eventually goes away - either on its own, or after running a "wipe" pattern for a while.
My previous Samsung plasma had this problem. If I was watching a bright scene and then the scene suddenly changed to a dark scene, there would be a "ghost" of the previous bright scene still visible for a second or two. It was very annoying.
c) Uneven Pixel Aging. This one is a bit different and sometimes people freak out and think that it is burn-in, but it is not. All plasma displays gradually dim over time. Each pixel emits its own light. You can think of a plasma display as being made up of several million individual tiny little light sources. Thus, each pixel will age and dim completely independent of all the other pixels.
So let's say that you play a video game that has a white HUD. The pixels that are displaying that HUD are going to age and dim more quickly than all the other pixels because they are showing a brighter, white image all the time whilst all the other pixels are changing and are showing darker images (not pure white) most of the time.
I've been playing a lot of Left 4 Dead 2, which has a white HUD. If I put up an all-white screen on my Kuro, I can clearly see where the white HUD pixels are a bit dimmer than all the other pixels. It's like a negative image of the HUD.
Now, this is not burn-in. The HUD does not appear on screen when I am watching a movie or TV show. If it were burn-in, I'd be seeing the HUD, regardless of the content. And it is not image retention. If I go to the pause screen on the game, the HUD does not linger for a moment or appear to stay on screen in any way. No, this is just uneven pixel aging where the white HUD is causing those few pixels to dim more quickly than the rest of the screen. Thus, this form of image persistence is only visible with basically an all white screen that can make it clear that those few pixels are now dimmer than the rest of the screen.
NOW, let's be clear that LCD displays can suffer from various forms of image persistence as well. The way that an LCD display works is that the liquid crystal present in each pixel "twists" when an electrical current is applied. As the crystal strands twist more and more tightly, they block out more and more light from the backlight, which gets them closer and closer to appearing "black". When the voltage is removed, the crystal strands "relax" and untwist, allowing light to pass through again and appear closer and closer to "white".
Over time, some pixels "forget" how to "relax" or twist all the way if they are not "flexed" on a regular basis. Ask any LCD owner who watches a lot of 4:3 content with black bars on either side of the image. Those "black bars" end up being partially visible, regardless of the content, after a long time. Basically, those black pixels "forget" how to untwist all the way, so they partially block a bit more light than the pixels in the middle of the display. A similar thing can happen in the opposite direction where a constant white image causes those pixels to "forget" how to twist down fully, so those pixels always appear a bit brighter than the rest of the screen.
So no display - other than DLP - is immune from all forms of possible image persistence. To be honest, you are more likely to see some form of image persistence with a plasma. But do be aware that you are not "in the clear" just because you buy an LCD.