It has occurred to me that I could use the scalarref's value to be the ID key for the object, which gives an added bonus of easy stringification.

That would deny any other class in the inheritance tree to pick its own implementation. One of the nice things about Inside-Out objects is that a subclass or a superclass can use traditional objects to do their implementation.

Given that Storable has hooks to deal with cases where classes have proper encapsulation, IMO, that's a heavy price to pay.