Thanks for those details. For now I will probably continue to sync by copying the newest .plist onto the other device during a sync, but I initially emailed the file and that worked fine (of course).

My old Palm Pilot synced in a way that seems a perfect match for this, but probably iTunes can't really run a program quite like Palm Desktop. I suppose the sync intelligence would have to be in the device itself? The more I think about it, the less easy it seems since two different .plists would have to be compared for a 2-way sync. With iTunes, the device would have to compare its own .plist with the one on iTunes and then generate (and save to both places) a synchronized one.

For me, the whole-file sync is enough because I can remember to only edit the song list on the iPad.

Thanks again for everything you do!