Sorry for the late reply. Came back to this thread for another reason and noticed your reply. I didn't experience the framing differences that you did. You experienced severe focus breathing, something which varies with different lenses. In any case, taking the 1.6x crop from the center gave very similar framing in my test. I didn't have to adjust the distance to be much shorter than 1.6x, nor crop more than 1.6x.In your examples I understood you moved back 1.6 times for the crop camera shots, and then just enlarged the resulting image to match the magnification of the ff camera.
My methodology demonstrated that is not a valid way to get accurate results considering the original premise was to move back with a crop camera to get the same framing as a ff camera and hypothesized you’d get 1.6 times the dof.
Perhaps more importantly: if I had cropped more than 1.6x, it would still prove the point. Let's say, with a particular lens and focus breathing, you had to crop 2x to get the DoF gain I saw. That means you could take a mft camera, back up, and get more DoF for the same framing.
If I had used a crop camera with that lens and adapter I would have gotten the exact same results. I don't take a position either way as to whether or not the DoF was exactly 1.6x (I didn't photograph something which would allow me to make such a precise measurement), nor as to whether or not the gain is worth it for a macro shooter (i.e. would result in fewer frames to stack). The point of contention was whether or not a crop shooter would get more DoF for the same framing (which would be less magnification), not how much or how useful. And the answer is, of course, yes. Anyone who has ever shot macro with a Nikon 1 or a cell phone, where there is no splitting hairs and the macro DoF gains are very large for a given framing, would find it hysterical that this became a debate.Your methodology results in exaggerated differences in the crop cameras favor.