Another lawyer here (tax, UK) - there are similar products available and they're pretty commonly-used over here (such as Worksite for DKMS/version control and Workshare for comparisons between docs).

But the VC tends to be centralised, rather than distributed. I've often hankered after a more git-like experience when working remotely or offline, and I will follow this project with interest.

One area that is underserved at the moment is diffing .ppt files. Since a lot of the tax industry in particular uses PowerPoint for step plans and structure papers (because it is generally easier to build structure charts). Whilst it isn't the right tool for the job, for as long as people continue to use it, getting this working on your app would be huge.