It would be extremely useful to have an option to be able to delete all corresponding SubGroups when deleting a Group (quasi Parent-Child relationships). Anyone who has ever deleted a Parent Group (e.g. when an employee leaves the organization) knows what a pain it is to delete all the SubGroups that the user might have created. This would be such an easy change, simply add another option "Remove Group Structure" or words to that effect.
My company uses Groups/SubGroups extensively ... it is a wonderful option in Act until you need to remove an entire Group Structure.