JoeyH wrote a while back some thoughts on why he hates the DGT SVN repo (mainly our policy to import just the incomplete source of packages - usually just the debian/ directory).
He updated that blog entry and latter said:
Update: I realized after posting this that while the space gains on alioth might be illusory, there is certianly a space gain for people checking the whole repo out. What's really needed is a way to keep all the upstream sources in svn, but check them out only when wanted, and check out all the debian directories for cross-game work.
I was thinking, how about having a different area of the repo where the full source is present and which pulls the debian directory as an external from the current location?
I know it has the huge disadvantage that anything outside of the debian/ directory, but part of the diff, is, for sure, lost. (Still, there is also another team policy to not track anything outside debian directly, except through patches, except for really exceptional cases, but even then, there is a need for a strong justification).
Would that work? (I know git-svn doesn't support externals properly, yet, so there's not much gain).
 I know Joey, you hate those, too