I think about this constantly also Don without making any comments in your threads - mainly because I'm at a loss to come up with any definitive comments.
Astigmatism, which is obviously present could well be the cause of the seemingly "laterally blurred" outcomes - I would be surprised if an SCT scope had this as a major manufacturing defect but I guess all things are possible...
I will dig out some old planetary images if I can find them (might be very hard though...) where I had captured Mars with an astigmatic scope - I have this strange notion that there was some sort of "smearing" of the features but it was quite a long time ago.....
This thread where a couple of old planetary imaging comrades discuss the issue are worth reading - particularly Glenn Jolly's (DesertRat) with the animation of Mars which you will need to click on to get it working in Post #10 here: https://www.cloudyni...ct-on-imaging/
Glenn mentions "de-centred correctors" as a possible cause but I have no idea how they are held in your scope - the old C11 used cardboard shims to centre the corrector in its flange whereas the C14 has adjustable nylon-tipped grub-screws in the flange to set the corrector alignment...no idea about Meades.
Kevin (astrovienna) who has been seen here again recently comments in the thread I've linked to...& he made a lot of test images & went through a lot of conniptions trying to nail the matter down way back when...perhaps PM him for some more info (Glenn rarely appears here nowadays) but for us cooling & seeing play strong roles in determining what your defocused/diffraction rings look like!
You can send yourself crazy googling "planetary images from an astigmatic telescope" just on CN.....SCT's very often appear to display astigmatism - we get oval diffraction rings after rapid cool-downs (remembering we use salted ice to very rapidly lower the temperature of our C14's primary) but we do have a temperature gauge to monitor the primary & always allow for a "primary relaxation period" after the rapid cooling.
In these situations the diffraction rings revert to the more circular pattern as the night wears on but it is important to remember that an oval appearance will often be seen in defocused stars regardless with SCT's as does the "trefoil" appearance also...but neither produces much of a problem in imaging...I imagine that you have nailed down the cooling/acclimatisation situation but thought it worth mentioning.
Further reading to send you crazy would be this recommendation https://www.cloudyni...ormal-in-scts/
If I haven't confused you further with the preceding, it should be said that these aberrations whether seeing/temperature or actual optical in nature (or both!) can make collimation much more of an issue, so I guess it's worth stating that a night of good seeing where your scope is thoroughly acclimatised would help you no end..!