[blakley]

I have the 75 Summicron ASPH as well as a 90/4 Macro Elmar and an older Elmarit.

I must say I hardly ever use the 90s; the 75 is just so good I can't justify taking it off the camera. The 75 is not quite as sharp as the Macro Elmar, but that's the highest standard I'm aware of. The 75 is sharper than any of my other lenses, and its bokeh is better than any other lens I own except the 50/1.2 Noct (aspheric). The focus throw as you observe is a major advantage, and the .7 meter close focus lets me frame almost as tight with the 75 as with the 90s, and at close focus the 75 does not unpleasantly distort faces when used as a portrait lens.

I'm attaching a shot with the 75 and M8 at close focus, cropped from sensor dimensions to 8x10 (that is, cropped horizontally but not vertically).