The "softening" effects of sulfite are dramatically overstated by people. One must look at the formation of image silver at microscopic levels to see why. Studies have shown the differences in true acutance (excluding edge effects) to be immaterial in many cases. Where differences do exist, they are significantly smaller than the corresponding differences in granularity, and the pH of the developer has a lot to do with granularity. Furthermore, the effects of sulfite levels in a developer formulation are very dependent on the film. Myths abound when it comes to image structure and definition. The subjective impression of sharpness is heavily influenced by edge effects and granularity. One study by Richard Henry showed that Rodinal produced relatively pronounced edge effects with the films tested, and increased granularity. It is the combination of these two effects that likely gives people the sense of sharpness when it comes to Rodinal.