A proposed Subversion vision and roadmap

I've been working on two sizeable SVN repositories through git-svn for a couple years, thereby enjoying an efficiently-stored mirror of the whole revision history, fast disconnected mode operation, history rewriting, and other Git features, while not interfering with the choice to keep using the historical SVN repository.
For both of those repositories, the directory trees under /tags and /branches, that Git recreated to match the SVN semantics, take up hundreds of megabytes...