This is one region where Mercurial particularly shines: things like hg-git and hgsubversion. I believe hgsubversion even supports translating from hg branches to svn branches.<p>(Git's model is restricted enough that it can't very successfully act as an interface for Mercurial or Subversion. Mercurial can do both very well.)<p>I had to use an SVN repository this semester at Uni. Only once did I actually check it out in SVN—then I decided to chuck that and use hgsubversion. That made me considerably more productive than the other students... especially when the SVN server ran out of disk space: I could still commit and push later, while they had to wait. :-)<p>When I have to deal with Git repositories, I typically use Mercurial, also.