I think LCD is the way to go now. We have a early (2003) Toshiba 42 in plasma.
It has been soing some weird snow thing, little white dots all over now and then, makes night scenes really annoying.
It doesnt do grey scale good, i dont think it ever did, and it has started to do ghosting, especially on night scenes also, if a person in a night scene moves, it will keep a light image of it for a few seconds.
Is your Plasma fan cooled? If not it's likely getting to hot in the back. I'm working on using PC fans to cool the back of mine. Right now I have a small stationary fan blowing on the back. This helps with the snowy things.