How could any serious developer consider subversion? It isn't even close to mature and has some serious administrative flaws.
At least CVS has been around for a while and the underlying structure is well understood. And graphing applications for the history of a file in subversion are not easy to come by.
What is worst about subversion is the inability to make a catastrophic check-in disappear. Anyone who argues that giving the administrator god-like powers is a bad thing (as the restrictive subversion treats the admin like a lowly untrustworthy grasshopper) clearly hasn't used Perl much where the philosophy is giving enough rope to hang oneself.
I've yet to have a convincing argument that subversion is worth looking at for a serious source code repository system yet (at least while CVS is so superior).