Do you have a list of tasks that are actually needed for the git cut over? As the actual tree conversion should be pretty easy, but I don't know what other back end infrastructure is run off of svn automatically. I am willing to help here in the near term, especially if that would get D6 in trunk.
On the Drupal 6 front, while I understand it takes more work to keep that running, the Drupal community always has 2 major versions supported. If this is going to put me on a tread mill that doesn't do the same, that's a real problem, especially as CiviCRM is looking to be the standard CRM for Drupal. It just doesn't cut it if CiviCRM doesn't support what the Drupal community does. What is needed to reduce that effort? Is that a statement of better automated testing to make it less work?