@lsmith77 unless you solve the issue of extending the document manager through composition properly, I would not introduce this interface. Having an explicit interface means you are stuck with it for BC reasons until 2.0. the ORM is facing it to introduce the second level cache, by needing to add a new method in the EntityManager (we may decide it is OK because we have a base class for the decorator, but technically, it isn't).
Any place passing ``$this`` as an argument will break the possibility to decorate the class (see the discussions about passing the Symfony2 dispatcher properly to listeners since the switch from inheritance to composition if you need examples). So I think allowing composition for the DocumentManager would require a major refactoring of the architecture of the ODM