You can just use riobackup from rmml.dev.java.net (works on the Karma and the Empeg) to backup your playlists ... It keys off of RID (the unique ID based on the music's content), so you can just download your music and reupload it whenever, and as long as your haven't modified the file (like reripping it or something that would modify the music data), then riobackup will be able to restore your playlists.

Tony can probably give you more details since he probably uses it more than I do (or he did, anyway)