I'll check this out!
Looks good, and havent come across it before!
Despite constantly Googling for backup solutions and replacements for TimeMachine!
Side note: I recently put together a TrueNAS Scale based NAS box for TimeMachine.
It's running 5x 4TB drives, using ZFS RAIDZ1, and it's the best network multi-user TimeMachine destination I've ever used! (short of a large direct connected TB SSD)
It's much more responsive to browse and restore over my LAN than I'd have expected!
If you have a file system like Zfs that gives you snapshots, you would not need a tool like oP’s to make multiple copies. You can periodically do rsync(think cron job), and literally include the —delete flag such that rsync tries to replicate source and destination. The trick is to keep making cheap snapshots on ZFS such that those deletions are captured in the snapshots. When you need a file that was deleted a year ago, or as of a year ago, simply browse to the snapshot of that time, and get your data back. Zfs stores the delta only anyway, so they are quite cheap.
This is how I backup the primary storage of a huge HPC cluster - 2.5 Petabytes of research data.