Is there any support for that? (Of course, for a large enough hard drive, it's not much of a problem...)
http://www.synctus.com/ddar and http://github.com/basak/ddar
It's recently been made available on Homebrew, too.
That's right.
It's a simple tool that does a simple job. It's pretty much done.
> How reliable is it currently?
No known bugs.
> bup currently has no way to prune old backups
This does deduplication, but can also encrypt the deduplicated blocks and store them on (say) S3.