Do you plan on supporting synchronizing with other systems such as Trello, HP ALM, Bugzilla, etc.?
At this time, the short answer is 'no'.
Our goal is to provide the best experience for Jira-to-Jira synchronizations. Supporting other systems would require us to make tradeoffs regarding the supported feature set, as all systems have different capabilities. At this time we do not intend to reduce Backbone's functionality to become a common denominator for these scenarios.