No question that the majority of debates over programmer tools distill to either personal choice (by the user) or design emphasis, i.e., optimizing design according to particular uses cases (by the tool builder). Text Editors are probably the most prominent example--a coder who works on a Windows at work and codes in Haskell on the Mac at home, values cross-platform and compiler integration and so chooses Emacs over Textmate, etc.

It's less common that a newly introduced technology is genuinely, demonstrably superior to the extant options.

I wonder if this is in fact the case with version-control systems, in particular, centralized VCS (CVS, SVN) versus distributed VCS (git, hg)?

I used SVN for about five years, and SVN is currently used where I work. A little less than three years ago, I switched to git (and gitHub) for all of my personal projects.

I can think of a number of advantages of git over subversion (and which for the most part abstract to advantages of distributed over centralized VCS), but I cannot think of one contra example--some task (that's relevant and arises in a programmers usual workflow) that subversion does better than git.

The only conclusion I have drawn from this is that I don't have any data--not that git is better, etc.

My guess is that such counter-examples exist, hence this question.