Hei there. Great project! Testing right now.
Just like to add something.
In the past, I was using some rather tricky scripts that created vss snapshots and deleted it manually, and for backup, I was using Exdupe, which is a rather nice tool (http://www.quicklz.com/exdupe/
Now, I know that the source code is available, but not sure if the licence terms are compatible. Maybe, it could be integrated with this tool somehow, so we´d had both compression and deduplication in an awesome tool.