At Isode we've running code for a similar protocol which we refer to as "IQ Delegation" for delegation of IQs to a component. One of the things we learned in doing this is that it not terribly wise to forward the delegated stanzas and any response stanzas to the component directly over XMPP. Instead we encapsulate the delegated stanza in an IQ which requests the component to process that encapsulated stanza and the result of that processing then provided encapsulated in the response to this IQ. This provides, we believe, semantical separation necessary to well implement this. Without this separation, it is hard to difficult to handle arbitrary extensions and certain error cases.
This IQ query and result payload element uses the XEP 297 <forwarded/> for the encapsulation. -- Kurt
