It occurs to me that there are three components to the microcontrast game. One is how rapidly the image changes from black to white, or or vice versa, when there is a sharp step in the exposure. A second is the "ears" you see in PE's example - the additional density at the edge. The third is if there is any lightening on the white edge of the step compared to the average lighter density. Developer composition, dilution, and agitation can effect all of these differently and thereby produce different visual effects.