If you don't mind, I'll jump in on this thread:
When you say "UFS" do you really mean "UFS" or do you mean the "UFS2" that FreeBSD, others? now use?
Because I would REALLY like to know to what extent linux supports UFS2 since I would like to be able to share files between a FreeBSD and Linux dual booting system.
Also for your situation, potentially you could consider:
http://en.wikipedia.org/wiki/ZFS#Mac_OS_X
If you're using Snow Leapord
I know there's a project to make this work on Linux via FUSE, I think it's recently left beta, I have no idea how reliable it is.