Thank you, the details, though long, were very interesting :)

BTW, I think the relevant links for ESR's cvs-fast-export and repo surgeon are probably http://esr.ibiblio.org/?p=4761 and http://www.catb.org/esr/dvcs-migration-guide.html, plus his recent blog. I think the rough history is that there was a tool that mostly worked (taken over by ESR from someone else, I think), but in the last few weeks, he suddenly got serious, make it a lot faster, wrote a decent guide, etc.

Yes, I've had very good results with reposurgeon. As a downstream of Simon's, I'll probably be using this to rewrite the halibut and putty Debian packaging repositories into forms that make them appear as though they have always been based on the new upstream git repositories, unless Simon tells me that's a terrible idea. (This will be a non-fast-forwarding change, of course, but since I'm the only direct committer to both of those, I think that's tolerable.)

into forms that make them appear as though they have always been based on the new upstream git repositories

We have always been at war with git-svn. Oh no, wait, we have never been at war with git-svn. :-)

(Seems sensible enough to me. I've just been figuring out how to do the same thing to the more convoluted of my old informal git-svn checkouts using git filter-branch rather than reposurgeon...)