I'm currently evaluating `bupstash` (also written in Rust) as a replacment. It's faster and uses a lot less memory, but is younger and thus lacks some features.

Here is somebody's benchmark of bupstas (unfortunately not including `bup`): https://acha.ninja/blog/encrypted_backup_shootout/

The `bupstash` author is super responsive on Gitter/Matrix, it may make sense to join there to discuss approaches/findings together.

I would really like to eventually have deduplication-as-a-library, to make it easier to put into programs like nix, or also other programs, e.g. for versioned "Save" functionality in software like Blender or Meshlab that work with huge files and for which diff-based incremental saving is more difficult/fragile to implement than deduplcating snapshot based saving.