GNOME considers DVCS choices

I think that a large portion of the effort of converting from CVS to SVN was in figuring out what the projects actual history was (figuring out when files were moved within the repository and turning that into a history where the file was in the original location until it moved; figuring out which modifications were in the same commit, etc). SVN is able to represent project history in a clear way, and people are less likely to do strange things, so moving to another system is not so difficult, and the work of getting there from CVS would have had to get done anyway.

The tools for importing to git from SVN, for example, are pretty straightforward. The tools for importing to git from CVS are complex and do a lot of guessing about things that git needs to know that CVS doesn't preserve.