Yeah, I bought a 2009-era MacPro on the very premise that it would make a good ZFS box (ECC memory, slots for 4 drives, etc.), based on Apple's promises (denied!) for ZFS. Every once in a while, I look over at the open-source ZFS universe, which does support the Mac, and my only conclusion is "very cool, but I wouldn't bet my data on it."

Relevant and depressing links:
http://www.reddit.com/r/usenet/comments/1xneid/migrating_to_zfs_on_os_x/
https://news.ycombinator.com/item?id=7457917