BuddyPress.org

@intimez – not sure about about export, but you can use the import for Ning as an import option (more of a workaround). read…

https://buddypress.org/community/groups/how-to-and-troubleshooting/forum/topic/importing-data-from-excel-csv-sheet/
and

Import from Ning: Import Ning users to WordPress and BuddyPress