The stab is there for several reasons...one is to optimize your attitude in cruise and autorotative descents. The other is to keep your nose from being too high during a hover and transition flight. When in cruise flight, the stab programs from down to in the neighborhood of level (depends on airspeed, etc). During an autorotative descent, the stab programs up to keep an optimal attitude. During forward flight, it basically acts as an airfoil to keep the nose attitude optimal. When in a hover and transitioning, the stab can't work as an airfoil so the stab slews down so that the rotor downwash hitting it doesn't cause an unnecessarily nose high hover (the 60 likes to hover a couple of degrees nose up). If you turn off the auto control and keep the stab at 0, you end up hovering a few degrees higher than normal. If your stab decides it doesn't want to play anymore and you happen to be clipping along at high speed close to the ground when it programs full down or has an actuator hardover, you're probably going to end up with your nose pointed at the ground and a few seconds to say "shit". Stab failures at low alt killed a couple of army folks when the 60 first showed up.