In my opinion the G20 is a significant upgrade compared to PX80. Just to mention a few points:
- FullHD panel
- Better contrast (better blacks, but more signicantly G20 is brighter)
- Less reflections in the panel compared to earlier generation plasma's from Panasonic
- THX setting making life much easier when setting up the TV at home
When that is said, I would probably wait for a review of either V20 og VT20 for which at least I have high expectations. I of course don't know if these are above your budget.
There are also other great plasma's to consider this year from Samsung and LG.