One last thought experiment from me This time, instead of keeping the focal length of the lens fixed, change it but fix the shooting distance.

In this case, think of scenario in which your camera-to-subject distance is fixed - like shooting a football game from the sidelines.

You are there with a 50mm f/1.8 and the person next to you has a 500mm. You both shoot the same scenes from the same distances using identical exposure settings. If you were to crop your 50mm images at 10x they would look just like those shot with the 500mm - the same spacial relationship between the players and the background. The only thing that would be different (aside from the obvious degradation in IQ) is the DOF. The cropped image would look as one would expect from a cropped image.

So a format that touted a 10x crop factor (in which a 50mm becomes effectively a 500mm) would produce this apparently highly magnified image with a deep DOF. But definitely not the same image as the SI guy with his 1Ds because of the DOF only.