Ok, so I see that I may be one of only a few that would want this functionality... let me try to break it down a bit more.
1. Drives are becoming bigger and cheaper every day.
2. I don't even use half of my current 60GB space.
3. If I did I could easily par out all the stuff I never/rarely listen to.
4. I travel a lot, and like to have storage/music with me, so until I can put 25GB of stuff on an Ipod I take my RIO.
5. Yes, I already have all my music collection backed up and striped on another machine.
6. If one of the drives goes down (hardware failure) then I still want to have music on my trips.

7. It just seems like an easy/simple/cool feature to have. I could just use the Hijack menu to select the drive that gets accessed.

thanks for all your thoughts.
-Arioch

side note - jEmplode rules. (except for a few bugs)