Many things will depend on how the system is supposed to work. And the problem is that manuals that describe the system are not well written, and knowledge thereby becomes lacking. Many of these systems will not hold heading in the hover, as the yaw channel is very slow to react. Once in forward flight, heading hold should be done through the roll channel, and the yaw channel relegated to turn coordination. But you have to know the system intimately to be able to tell this.