Hi folks, we just got a quote for a GFC-500 to finish up our new Garmin panel in our M20F.  We've been without an autopilot since we bought the plane.  It had an old S-Tec that was inop and not worth repairing. We've heard that some don't think it is worth the extra cost for the adding the rudder/yaw controls.  I really have several related questions: What do the A/P yaw controls add to a plane?  BTW, we don't have a rudder trim.  Would this be a poor rich-man's rudder trim?