Provided you did the following:
- move your music to the linux ext3 filesystem
- run mp3tofid
- rsync to your player
- add or change this through samba on a windows client
- run mp3tofid again
- run rsync again

then you should see mp3tofid only rescans changed and
new tunes, unless you force it using a commandline switch.

If mp3tofid did not rescan unchanged tunes on the second
run, then the second rsync should be fast too.

Pim