This is exactly what I want for Linux (headless), but I haven't been able to find anything like it. The closest thing I've found is attic, which, while amazing, requires a daemon to be running on the remote end (which is what makes checking, deduplication and deltas fast).
Unfortunately duplicity is very inefficient, it needs to reupload the full set every so often, which takes up a lot of bandwidth. I guess attic is my best bet in the foreseeable future.
Does anyone know an Arq alternative for linux?