
If you use the Duel Adapter for P2 data transfers with a Mac laptop, do not upgrade to Snow Leopard. There is no driver to support the card, for that matter, my recollection is that Duel seems to have stopped developing Mac drivers for their card some time ago. There have been lots of complaints about reliability and compatibility with Duel Adapters, but they've been the only game in town if you want to import a single P2 card with your laptop (and not tie up the camera). I personally have not had any issues but there are a lot of complaints out there.
The good news is that Panasonic announced that they will be releasing a single card P2 card reader in Spring 2010. They don't say what the interface will be. Let's hope that somebody makes a Snow Leopard driver for the Duel card before then.