Yeah, a few years ago I steered our university research group towards using ZFS for a couple of new servers with 1.5PB storage each (2.0PB before raidz2), on RHEL (would have preferred Debian). Absolutely no problems with the system. The IT guys were a bit doubtful whether it would work well, for instance they insisted that XFS would be better at managing parallel requests, but when the system happily saturates a 10Gb ethernet with plenty of bandwidth to spare I don't think there's a problem. We have had ZFS flag up one hard drive so far that was returning false data, which was then hot-swapped out. Other filesystems would probably have just suffered data corruption without us knowing it.