Paul, do you know whether Greiner made the comparison with the focus set at the infinity stop, or at a near subject distance using careful focusing on the live view at 100%?
Any comparison made on a distant subject with the focus set at the infinity stop is potentially, and dare I say, likely to be, misleading.
He mentioned something on the horizon (eg some kind of tower) with some minute details seen on the 138, but not on the 180. Maybe comparable to when you can discern an individual letter in a distant sign in a larger scene with a monochrome sensor and then with the colour sensor it is a bit blurred …
If you look at the FOV Alpa viewfinder thread in the simulated cutouts you can see that 138 and 180 are not that far apart.
This is why it would be interesting to validate whether effectively the 138 can cover everything after 90mm more or less; below 138 via stitching and the 180 by sheer brute force resolving power meaning it is almost the same to shoot something with the 138 and uprez it’s to the size of the 180 frame.
But then again - the 138 is the newest design and costs 15-17k and the 180 is a Digaron S which came out a decade if not more earlier than the 138.
Indeed, the the 60 XL and the 138 would cover a lot of ground in a two lens kit; never thought about this combo …