borg replaced https://rdiff-backup.net/ for us and gave: * nice speedup of backups/backup tests, * decent saving in the disk space thanks to compression and deduplication, * decreased backup replication time [ borg repo tends to have much less, larger files compared to rdiff which has in its repo at least as many files as your source data; rsync likes it ].
to finish backups in a reasonable time we had to parallelize backup gathering [ each server / vm goes to separate borg repo; this limits a failure domain in case of corrupted repo, but denies us benefit of deduplication on larger scale - across servers ] and borg archiving. without that - we would be a limited by a single cpu core performance [ borg is not multithreaded yet ].
it's worth testing the backups - we're doing it each day by using borg's repo self test and by extracting few key files and checking their checksums and content... just in case.
echoing other comments - https://kopia.io/ looks interesting but we have not tried it yet.