Todd, your tests prove one thing, the differences are very subtle between the two lenses. It is remarkable that a lens with a 40 yr design can even compete with a state of the art brand new lens that costs almost 10x as much. I must admit, your tests made me purchase a 105 2.5 P.C. It has been sitting in a box for a few days waiting for me, can't wait!
When I had the ZF 100 and Nikon 105 2.5 AI-S there was no comparison in pretty much every are....bokeh, sharpness, contrast, etc. The Zeiss was far better. I got rid of the AI-S. THEN....I saw your 'useless' comparisons and see that you are using the P.C....which is what I have heard is the best of the 105 2.5 bunch. Found a deal I couldn't pass up for one in like new condition. If it is anything like yours I will consider it the best bargain I have purchased.
To afm901....as others have mentioned, there are slight differences obviously and everybody has different needs. Everyones thought of the better lens to them applies to what that individual needs. Hey, an 18-70 f/3.5 may be a better lens for some than a 24-70 f/2.8. You are correct, you can't throw a blanket statement out there that all Zeiss lenses at all lengths are better than the Nikon equivalent, but the Zeiss lenses are fantastic and have the following they do for a reason