My motivation for trying out git-svn is the effortless merging and branching. Then I noticed that man git-svn(1) says:
Running git-merge or git-pull
Rebase the local git branch onto the master git branch then dcommit and that way it looks like you did all those commits in sequence so svn people can see it linearly as they are accustomed to. So assuming you have a local branch called topic you could do
git rebase master topic
which will then play your commits over the master branch ready for you to dcommit