Hmrz. Bottom of the line 1080p Pana vs superceded non-Elite Pioneers. Interesting!
I'm positive they will be very hard to find, but I've read that the 5020 has 5x better black levels than the 5010.
I have reason to believe that the Panasonic top of the line V10 series is superior to both the 5020 and 5010.
The one thing that the 5020 might* have over the V10 is motion resolution, which is, so far as I know, not even a truly accepted metric yet.
I will assume the V10 will have the best shadow detail of any TV mentioned here so far. It does not apply 3:2 like the S1, has far more consumer-level pic controls, add THX mode to that, and from my personal experiences, the video processing differences are easily discernible with different Pana models, when side by side with the same source material.
I don't know how this thread went from BEST 50" TV, straight to the bottom of the line Panasonic, but if BEST still matters, I'd keep hunting for a 111 or 500M, and less those, get the V10. Mebbe the 5020, but I'd probably go V10.