Thank you for your efforts at trying to improve the demosaicing. That is greatly appreciated.
It is absolutely true that such problems that I pointed out can be mitigated in a variety of different ways. In fact I was the first to point that out in my OP. But for the very same reason that I abandoned Lightroom's demosaicing in favour of AMaZE, mitigating such issues gets to become a tiresome exercise. Minimising issues at the starting point makes digital processing life significantly easier, as per @chroma_ghost 's story.
It is also true that I have a critical eye worst than most. When I started photography I had very little money to spend on high-end equipment. I have a number of files in the 10-21 MP range, which are important photographs to me. While I know I cannot make 40x50 inch prints from some of them, some can be stretched to 32x40 inches. Some of my clients come to me with very low resolution images, and want to make large prints. Once I had to make two 1x1 meter prints from a 6 MP image. It was a real battle. The vector-based upsampling that Photozoom Pro uses was a huge help to maintaining the thinness of edges.
The point of all this is to avoid anything that shouts 'digital' in our photographs. Halos, mazing, zippers, pixellation, jaggies are all quite hideous in a print. Minimizing artifacts as far as possible makes them look very natural, even on close inspection, whist having low to invisible noise and with thin, crisp edges.
One can just avoid sharpening altogether and end up with a softer image but with no visible artifacts in a print. This is what I'm doing today to avoid enhancing the issues. But with a cleaner file, one can have a crisper looking print at the end of the day. While that may be insignificant to most, I am not interested in resting on my laurels. If something can be improved, why not?
I admit this is totally new to me. Could you explain or direct me to an explanation of this lens optical behaviour that creates ringing?
All in good spirit! Sharpness is a bourgeois concept. We are at aristocrats' level looking for things smaller than sharpness...
Otherwise, tell me, why would the RT authors be so interested in functionality for at looking at 1600% for pixelshift? Why do we even need pixelshift? Look at those billboard size Shot-on-iPhone prints. Are those good enough? Maybe for some!
None taken Though if I ever had such a club, members will qualify only if they can see the jaggies with their own eyes, without further visual aid. LOL Regular corrective vision spectacles are fine. No bionic enhancements, binoculars, microscopes, loupes etc. *Joking!