Greg,
Through my investigations I've found that CCD Inspector can be very helpful, but one needs to take at least 10 dithered subs (20 is better), and calibrate them before making measurements. Stars need to be sufficiently exposed too (not too short, not too long). Then results given by CCD Inspector are very precise each time. It allowed me to fine-tune tilt in my imaging train and now PI reports eccentricity in my subs just under 0.29, which equates to 96% round stars across the entire frame.
Paul - the stars are really good now, but I feel that like me, you won't stop until you will get star shapes at least 95% perfect
