I might give that a try, there's a package on my distro. Is it fully stable? Reasonably fast?
I'm using it for about a year now, didn't have any problems so far. The only downside for me is that Borg is a command line backup, and I'm doing backups only rarely, so always forget how to backup. Made some scripts.
There is also a 3rd party GUI for Borg, don't recall the name. When I've tried it, I've noticed the GUI (not the Borg) was saving a password in clear, in a text file, so I've decided to use Borg only, from command line. Made some personal scripts for the preferred compression.
Borg is using some sort of cache with checksums needed for deduplication and incremental backup. If you keep that cache locally, at future backups it will be very fast. First backup took many hours, then from there on, it only takes minutes. The cache is discardable, but if you delete it, it will take again a few hours to rebuild it at the next backup.
TL;DR, so far worked without hassle for me, to keep backups for a few TB, from Linux to an external NAS. Don't have much experience with other backup solutions, so I can not say how good it is by comparison with other backups.