You can obtain the play counts and Wendy information from a stock empeg using just the normal emptool protocol. You can't, however, obtain the tuner presets, EQ settings, or bookmarks without installing third-party software on the player, such as Hijack.

And as you need Hijack's FTP server support in order to get the tuner and EQ settings, you might as well use it for everything, especially as clients are so easy to come by. You could, in theory, use the REST command to implement rsync over FTP, but in practice, backup isn't time-critical (leave it overnight) and so it's probably more effort than it's worth. If you don't mind a dedicated empeg backup, unconditionally retrieving the dynamic partition and then retrieving config.ini and all the fids if they've changed size or date, would be good enough and probably well under an afternoon's work in python. If you additionally want the PC-side version of the music to be usable and playable, you'd have to work a bit harder, and as the obvious representation for the playlists is a symlink forest, it's not clear whether it would make sense to do that to a Windows PC.

Peter