Thanks for your comment about unix socket support. I went on and added a plugin last night so that Drizzle will handle the MySQL UNIX Socket protocol. It will be in the next beta.
As far VCS goes, my personal take on this is that they are all the same (assuming that they are distributed!). Our choice for BZR is more about Launchpad then the tool itself. LP is a wonderful sit to use and github is just a little too minimalistic. We have also found that users tend to pick up BZR more quickly then GIT, and that GIT support on Windows is really subpar. If someone finds that the feel strongly enough about GIT, I am sure that a mirror could be run.