To match Displacement from previous version versions of RenderMan, the following conversion may be of use:

To get a similar tessellation level, using a shading rate (deprecated) value of X would translate in using a micropolygonlength value of sqrt(X):

shading rate = 0.25, micropolygonlength = 0.5
shading rate = 1, micropolygonlength = 1
shading rate = 4, micropolygonlength = 2