A couple thoughts... maybe I'm missing something. Isn't SnapRAID essentially the same concept as Unraid - parity calculated "externally" - Unraid does it at runtime, SnapRAID does it on request, but neither provides bitrot protection via detection. Simply by restoration (if I detect a file has become corrupted, I can restore from parity)
Also would be very curious how ZFS gets introduced, instead of XFS or BTRFS for a disk's filesystem, it would be simply a single disk zvol? I would expect performance could be more affected then. Also, seems like the only benefit there would be help detecting bitrot happening (which is a good thing)