There probably is some synergy with Scout, since it will help you line up action chains and also because when it does clear green it raises the chance that you'll hit an action. That is, assuming you don't have Nobles or Great Hall. In that case I think Herald and Scout start tripping over each other.
Although I think the best stuff happens when Herald hits a terminal. Herald+Bridge = Market+Highway. Herald+Smithy = Laboratoryx3.