I bought the VT25 at the end of 2010 (at the time it was the best 3D plasma around) I can tell you that I've never had any type of burn ins. Although initially when I was breaking it in, I did leave something for about 15 minutes and the image stayed for a few minutes after I came back. However, this was just after I bought it. Ever since I sometimes leave for 20 or 30 minutes
and I have absolutely no problems. I am not sure I could of said that 6-7 years ago models.
Plasmas do generate more heat though. I am currently looking for one of
these. I can tell you that whites are brighter on the LED, but blacks are definitely deeper on plasmas.
I guess ultimately your personal preference will help you decide.