"For me having ZFS is a major useful step in it provides both data checksums and file system snapshots. Though it remains to be seen if this is well-used (e.g. can you snapshot the OS partition/share before any update/upgrade to allow roll-back without also rolling back your own data? Is that the default option in the upgrade manager?)"
In this respect, just as with LVM snapshots - you can only snapshot whole partitions. However that shouldn't be an issue if you partition your disks properly. User data & sysem data are best kept to their own FS'.