Having recently come to the Airbus from Naval Aviation where our control deflections were always visually confirmed, I have always been concerned by this aspect of the flight control system. Since I cannot see ANY of the the controls move from the the flight deck, I have developed my own personal check. When I do my walk round I look at the actual control surface positions and compare them to what the ECAM flight control page displays. If the display agrees with what I have seen, then I trust it. For what its worth.