We migrated libgdx to github and so far it has been awesome there have been a lot of new contributions and using the pull request system is quite nice, you can see the proposed changes, comment on them, ask them to fix something and the pull request is automatically updated. In my experience the change to github is much more than the change to git, so I would vote for going to github instead of just using git in sourceforge.
P.S. I already made the 2.8.5 release of lwjgl in maven central, but it hasn't been synced yet