I'm using my unRAID for Mac OS X as well. I have one 750 GB drive dedicated to iTunes and another 500 GB dedicated to a number of TV shows I weak link into iTunes (basically save them there and option drag them into iTunes so it doesn't copy them to its folder).
I'm thinking I'm going to make this a bit more flexible by symlinking the TV Shows directory on one volume, the Movies to another and leave the rest for my music. I've got the rest of my 5 TBs dedicated to movie rips outside of the iTunes world.
Kevin