I have tried all-moving horizontal stabs on two models, and couldn't see much difference in performance. A further experiment with an all-moving combination fin/rudder was a total failure - about half as powerful as a conventional fin/rudder of the same total area, despite extreme deflection angles. The stab/elevator or fin/rudder combination acts, when its control surface is deflected, like a cambered airfoil, which can develop far higher lift than any thin symmetrical airfoil that is simply inclined to the airflow.