I've seen a firmware update on the polish Panasonic site: www.panasonic.pl
Unfortunatelly there isn't any manual about it, so I don't know, what upgrades are included in it.
My player has normal size subtitles, and correctly displays eastern European character sets. I think it's the news in this firmware.
I missed then "Zoom to Fit" function. I've movies, which are smaller than 625 lines. These are displayed in a box, in the center of screen. It also has problem with some audio track, although these are same as others, which can plays correctly.
If you will so brave to install, and it will good, please write a message to me!