The family photos story is what made the mirror point land for me. A RAID 1 copy feels safe until ransomware or a bad delete hits both sides at once, and then there is nothing to go back to. Your GFS rotation explanation also helped, because keeping 14 daily snapshots sounded enough until you showed how quickly the storage adds up. I had not thought about the 2 AM cron warning either, and testing restores is the line I am taking away from this.