As I noted in another thread, a few friends and I are looking at the possibility of partnering up on a "vintage" Mooney.  We've come across a few that don't have an autopilot but do have a (functional) PC system.  I've got a fair amount of M20C and E time, but both planes I flew had the PC system inop.  Assuming the system is in good order, how well does it work?  Is it effectively heading hold without the bug?  Manually put it on the heading you want and it "should" keep it there?  I understand