Biggest advantage of the alternative rockbox firmware for Archos jukeboxes is in my opinion that it comes with source and is being actively developed. As opposed to the official firmware upgrades which are sporadic and seem to introduce more new bugs than bugfixes.

The rockbox firmware has some games for the JB recorder, which probably has a bit more CPU to spare compared to the JB studio. They recently got playlist support working and are adding things like mp3v2 tag support, editable persistent playlists, etc. Basically trying to fix all the things that are annoying with the existing firmware.