Depends on how much latency/what big a time window for data loss between runs you can afford. We went from streaming cyrus-imapd replication to minutely send/receive for availability, but that introduces a 30-90 time window where data can be lost. Fine for us (esp. considering the reduction in ops overhead), but not necessarily for everyone.
(Backups are done by rsnapshot pulling from a snapshot, so we have another copy outside ZFS just in case.)
