Well your panasonic has excellent upconversion anyway. I have a bd65 (broken now) and it's dvd upconversion was AWESOME. Not equal to blu-ray obviously, but very, very good.
Yes, I've found the upconversion to be very good with the Panny. It's generally better than I even expected, but it seems to vary pretty widely from DVD to DVD: I wonder if anyone can explain that?
For some relatively extreme examples I've seen so far, this verion of
Der Rosenkavalier has rather poor video quality while this version of the movie,
The Fifth Element, is quite close to Blu-ray -- I'm not sure what "Superbit" is all about.
