(Sorry, I can't reply to the original thread as I wasn't a member of the
list at the time)
Can I throw restic in to the mix? It's very similar to borg, but super
fast. I moved away from borg a while ago for various reasons.
It's written in golang, so it's a simple ELF executable to deploy. Supports
lots of destinations and multiple keys .
Specifically, I'm thinking the multiple key feature would allow us to have
the client push backups to the backup server over a read-only connection
(SSH, S3, rsync, whatever), then be able to run restic server-side to
handle the cleanups.
Anyway, 'food for thought' that we can discuss.
 My home desktop backup: ~121gb of source data on spinning-rust (not
SSD); incremental backup takes ~8 seconds:
scanned 11482 directories, 72707 files in 0:01
[0:07] 100.00% 13.298 GiB/s 121.249 GiB / 121.249 GiB 84189 / 84189
items 0 errors ETA 0:02
duration: 0:07, 15798.45MiB/s
snapshot 8c4aea6d saved