Clap the DP on the back next time you see him. I can’t tell you how many people shoot 4×3 on the DVX and think it will be easier just to blow it up in post. What maroons.
That being said, you’re in an OK spot already if you just suck it up over firewire. You’ll be blowing the footage up 150% to fit in an HD timeline, but c’est la vie. Do you have a Kona card that will let you uprez on the ingest? That would probably be the ideal way to go. Cheaper alternatives include ingesting the footage as in into FCP, and then running it through AfterFX and have that do the blow up. After Effects actually does a good job at blowing footage up, changing frame rates, etc. Obviously not as good as a hardware conversion (Kona, Telenex, etc) but good in a pinch or for not alot of footage.
I would also cut the piece in an HD timeline, even though you’re going out to an SD DVD at the end. The picture quality will be better and you never know down the line if you’ll go out to blu-ray, or upload it to the web in HD.
What I can’t comment on is mixing Panasonic 30p footage with Sony 30p footage. Take in some of the SD footage over firewire and test it out in the timeline and view on a monitor. See what happens, or what else people post!