While this is nice, I think it should be emphasised that the blob-tree-commit-ref data structure of git is not essential to a DVCS. One of the disadvantages of everything being git is that everyone can only think in terms of git. This makes things like Pijul's patch system, Mercurial's revlogs, or Fossil's sqlite-based data structures more obscure than they should be. People not knowing about them and considering their relative merits has resulted in a bit of a stagnation in the VCS domain.