Great image Enda!
Any chance you could post a 100% crop of the bottom right corner? I'm really interested in the 28 for using with my P45+, but can't find any sample images (other than the test CI did with the IQ back) to have a look at. Curious about the quality of the image circle in the corners at 5/15mm shift.
Here is a crop of the bottom right around some rocks to give an idea of the contrast. There is zero sharpening on the image. Hope that helps.