Hi Paul
I think your LRGB images are coming along nicely, this is a good M42 just needs the sharpening modified as Greg has suggested.
If you are guiding off axis within the camera there is little chance differential flexure is causing those star shapes. If your guiding readouts indicate the autoguiding is going well then you should be getting nice round stars. It is most likely a collimation issue or as I have mentioned before perhaps even some variable astigmatism? The stars in your Lagoon shot look ok..?
you will get there I know
Mike