One practical point which might help one choose one version of Nikon versus another is not only the
max aperture but the working image circle. They might appear identical, but if you read the fine print, the f/4.5 circle is calculated at f/16, not f/22 as in most other cases. This means that at this
aperture the image circle will in fact be bigger; and given the fact that 90's are often chosen for
serious rise or other architectural movements, the performance near the edge of such images might
in fact be inherently better. Smaller max-apertures lenses are easier to correct - but it's the real world application which determines what distribution of sharpness takes the priority. And certainly
when you get past f/22 or so with a lens of this focal length, diffraction pretty much levels the playing field anyway. When I want extreme sharpness, I don't use any kind of wide angle design.