Backing up a ZFS volume would have detected the corruption error, giving you a chance to (a) not make a backup of the corrupted version and (b) restore a good v

Backing up a ZFS volume would have detected the corruption error, giving you a chance to (a) not make a backup of the corrupted version and (b) restore a good version from disk. In the same situation, HFS+ would let you make a backup of corrupted data. If you don't keep all your historical backups, you may end up unwittingly tossing out the last backups with good versions of those files. I'm sorry, I don't understand your last sentence.