Raised for mdoar:

I'd like to see an Admin tab for GH that would read an activeobjects.xml file and recreate the sprints in a supported way.

To migrate Active Objects data for GreenHopper, it's slightly complicated:

I wrote a Python script that used the GH REST API to extract information about sprints and their issues. Then a Script Runner groovy script read that data in and recreated the sprints in the new JIRA.