Using Github for issue tracking would be very community-friendly: people would not have to create yet another account (by the way, I still cannot do anything on Jira) or need to learn how to use a new issue tracker (that most likely they would very rarely use).
We would also benefit from the integration between repository and issues, especially if the github repository was promoted to be the official repository (not just a mirror).
There are of course somed drawbacks. Github’s issue tracker is extremely limited: it cannot be configured to support sophisticated software development process. Something would need to be done with existing issues: as usual, with yet another migration we would further deteriorate the quality of the database; if we don’t migrate the data then we cannot get rid of the current database for a good while.