I started working on something broadly like this in <
https://github.com/sourcefrog/conserve>. The things I most want to fix vs Duplicity are:
- fast random access to retrieve one file or directory from a large backup
- ability to get some files back out even if the backup is damaged due to a bug in the backup software or underlying layer
- don't need an entire backup layer to complete before you can get data back out of it
- (more in the readme there)
However it's proceeding quite slowly due to other demands on my time and isn't really usable yet.