If mp3tofid writes a "complete set" of files including FID 100, then presumably it's not meant to be run on a non-empty player?

mp3tofid writes a complete set of fids. But it relies on rsync to transfer the fids
to the player. The rsync command as suggested in the docs wipes away all
fids not created by mp3tofid.

Going back to emplode does not do this, of course. So before
going back to using emplode, you should probably resync all fids
to the old scheme, having recreated the fids with mp3tofid's -o switch.

Pim