Change Business Unit Permission

Ah, the CRM security model. Nothing is what it seems. I spent about an hour today trying to figure out what controlled the "Change Business Unit" permission and from what I can tell it is not the Business Management tab of a security role that controls this, but rather I had to give full permission on the Service Management tab for the following entities - Calendar, My Work Hours and Service as well as Search Availability and Browse Availability.

The security model continues to amaze me at times.