- The GitHub concept of forking would make individual developers branches easier to manage.
- The GitHub concept of forking and push-requests would make it easier for people who are not core developers to submit patches and for the core developers to review them and apply them.
- People have been complaining about flyspray for a while and the GitHub tracker is nicely integrated into the repository making it easy to relate issues to code and patches.
- The GitHub web-UI means that the code is easier to browse, inspect, view history (and relate changes to issues) than the "default" Git one that is in use at the moment.
- There would be no need for anyone to spend time or money maintaining/patching/fixing the SIP Router Git repo and flyspray.
- Someone else is handling backups and failure recovery.
- The use of markdown means that documentation and code can be presented together in a nice way with GitHub.
I am sure there are more too (which is why so many projects are on there now).
Peter