It would be convenient if besides delegating the "user", the "user+role" we could have an option to delegate combinations including the authorization groups and the roles of the person we are trying to delegate.
When a manager leaves on vacation and he wants one of his employees to take over, it would be convenient if he could assign roles and authorization groups to this person. This removes the need for admin to make sure delegated users have the roles and authorization groups needed to actually cover for someone on holiday.