Ours is 370GB. git-svn typically falls over and dies on that, if you're brave enough to try.

370GB is peanuts. Try keeping a centralized version control server up and operating when you have dozens of terabytes and thousands of developers.

Better to abandon the ultimately doomed monolithic repo scheme and tool your build and deployment systems to expect a multi-repo ecosystem. Then allow your teams to create their own repos on the fly, one for each individual project if they please. Once you reach that point, there is little reason to not use a more sensible VCS like hg or git.