Currently, all CommandDispatcher instances created from a given CommandDispatcherFactory share a single response marshaller. This means that the marshaller used by WF for its internal command responses is the same as the one used to marshal user command responses. This limits the extent to which commands may optimize marshalling of their responses, or indeed, use a different marshaller (e.g. ProtoStream).
We can remove the limitations above by using a distinct response mashaller for each CommandDispatcher.