well, for one its actually easier to use relative pathnames. You can easily create a mu3 playlist with winamp or xmms and just save that to a directory on the slug.
I do have firefly running on the slug, and shared the “music” directrory as drive Z:.
so I can easily use winamp to create static playlists, and just save them under z: somewhere. with the next scan firefly picks them up alright. 😉
Another thing you might be hitting with your smart playlist is case sensitivity. “Foo Fighters” might just be spelled with different caps, or more blanks. And then firefly fails. So it might be smarter (;)) to create a smart playlist like this:
where artist includes "foo" and artist includes "fighters"