+    def __format__(self, *args, **kwargs):
+        return self.__class__._member_type_.__format__(self.value, *args, **kwargs)
+

With this in the Enum class all members simply forward formatting to the mixed-in type, meaning that IntEnum behaves exactly like int for formatting purposes.  Another way of saying that is that the name attribute of an IntEnum member will only be used when the !r or !s codes are used.

If we are all good with that, then the question remaining is how should pure enums handle formatting?  Should they also go the value route, or should they go with the name?