Despite your rhapsody concerning the manual focus camera's great precision when set on a tripod and pulling focus from subject to focal plane, the Flikr photoset does not seem to show any photos where that method seems likely. Street photography with a long telephoto is going to result in a lot of hits and misses whatever the camera body. I think the first answer contained most of the information you really need. If a split prism is ever available you may increase your percentage of critically sharp exposures. Until that time, shoot bursts of several shots and pick the sharpest, learn to use the exposure bracketing if you don't like the exposures you are getting and change cameras if this one does not suit you. Older, 35mm bodies that would seem to be just what you are looking for are available for a tenth of what you paid for the D600.