I played a bit with the Nikkor AF 28mm/1.4D and AF-S 35mm/1.4G at minimum focus distance. Again, nothing scientific. I just pointed the camera hand-held on the leaf to compare the background rendering at f/1.4 without sharpening in Lightroom 3.
First the Nikkor AF-S 35mm/1.4G at f/1.4, second the Nikkor AF 28mm/1.4D at f/1.4, third the 28/1.4D at f/1.8, and fourth the 28/1.4D at f/2 (click on the images to open them in 2832 x 4256 pixel).
I moved the 35mm/1.4G at f/1.4 to the top and added 28mm/1.4D at f/1.8 and f/2