If you have ZFS clients and server, what benefit does inserting borg provide on top of a continuous ZFS send from client -> server and server -> rsync.net? ZFS send can already do encryption, and ZFS supports compression. And snapshots automatically "dedups" files that haven't changed between snapshot points, which I'd guess saves more space than deduping literal duplicate files which are not very common ime.

I guess I just don't see what value borg provides if you're already using ZFS throughout.