That sounds like a really good idea. You basically get the best of everything.

The cool thing about ZFS is the pool information is stored on the disks themselves. You can just plug them in and import the pools.

I decided instead to use ZFS. Better protection than just letting something sit there. Your backups are only as good as your restores. So, if you are not testing your restores, those backups may be useless anyway.

ZFS with snapshots, replicated to another ZFS box. The replicated data also stores the snapshots and they are read-only. I have snapshots running every hour.

I have full confidence that my data is safe and recoverable.

With that said, you could always use M-disk.