One thing that Shinobi could do was integrate well with the detectors on cam, so if your cam had person/vehicle detection or line crossing etc you could use that. That worked well.
But I too went from Shinobi to Frigate and I love it. The integration with HA is very good.
I have my important data stored on a RAID1 for some redundancy, but otherwise it's just snapshotted to an external drive plugged into my server. It's not ideal and I have two plans I really need to get around to implementing.
I have a detatched garage so I am going to set up another machine hidden in the roof space of the garage where I can have "offsite" backups. It won't get found if my house is being burgled (you need a ladder) and it's far enough away that it hopefully survives if my house burns down. My garage already has ethernet cable.
Another option would be storing some stuff at a friends place if you have friends that self host. I've also been meaning on setting a Wireshark tunnel to a friends server and we can borrow a little bit of each others space.