Edit: It's 10/13/2011 now. I've changed my mind. Tests ARE requirements. Requirements ARE tests. They are the same thing. If a test, especially the Acceptance Criteria alluded to above, describe requirements that would otherwise be missed, Rejoice!
The question is not one of hiding requirements, it is of size. I've learned that Epic Stories are beautiful ways to manage large amounts of information. Often the A/C for an epic are stories in their own right. That isn't something to avoid, it is something to embrace.