I continue to see people saying that "most panels don't seem to do this," in reference to the 2012 Panasonics. While I can't disprove the statement based on my limited sample, I have tested 4 different 2012 Panasonics (1 GT50, 2 ST50's, 1 VT50) and they all display similar long-duration IR performance. And that performance is very poor. Certainly worse than my old 5080, which has never shown any long-duration IR throughout 16,000+ hours of completely irresponsible usage. And significantly worse than the 60+ inch 2012 Samsungs (though the 51" models did display the same IR performance as the Panasonics).
I will concede these points:
-Most of the IR is extremely hard to detect unless you hunt for it on solid color images. And if you have to hunt for it on slides that means it's not harming your experience with the TV. (However I have seen some IR that shows on bright panning shots, or images of relatively solid color like sky shots. You also might notice it on flat-shaded cartoons).
-It always seems to fade entirely over a matter of hours (though sometimes a 100% fade takes long enough that it essentially means days of "normal" usage).
-It doesn't really impact users who will be viewing mostly movies, TV shows from DVD/Blu-Ray, channels like HBO with no logos, etc. Black bars are not an issue with this type of IR, so the only worry is high brightness logos and game HUDs.
Even though I'm happy with my GT50 I still feel the need to be highly vocal on this issue. I'd like Plasma manufacturers to know that people are concerned about this and want it fixed in future versions. Early reports from ST60 owners suggest that they may indeed have improved the IR handling of the 2013 models, but it's too early to be certain unless you have access to one you can test yourself.