(Technically, as Git is SVN compatible, so you could get this effect simply by using Git 'locally'.)
git2svn has a problem that we ran into recently: because git does not support hierarchical branching, if you do not keep all your branches in a single Subversion directory, it will take an excessively long time for a local git repository to synchronize with a Subversion repository.
For example, let's say that you have the typical /branches directory in Subversion. Now user "myria" comes along, and she wants to make her own directory of branches so that her own branches don't pollute the /branches directory. She does an svn copy of /trunk to /branches/myria/new-crypto. Now git2svn tries to import this change from Subversion into a local git repository and takes three hours. Why?
Because git doesn't support hierarchical branch names, from git's naive perspective, what Myria has done is make a copy of the entire repository into a new directory named "new-crypto" inside of her "myria" branch. Git does not interpret her commit as a creation of a branch - it sees "myria" as the branch, and "new-crypto" as merely a directory within the branch. Subversion gives no special meaning to the directory named "branches", so git2svn is simply using a hack of assuming that the "branches" directory contains objects that it can convert into git's branch objects. Git thus sees her commit as one giant commit of 100,000 files, and consequently takes forever processing it.
The above was a recently-encountered real-life situation at the office from about two weeks ago.