I was at the NWDA chat event and somehow I got to talking about craters. I decided to try making some and the results weren't quite as I expected. The transition from rim to ground is too sharp, as is the transition from crater walls to floor. I tried adding a PF to break things up, but no luck. If only there were a blur function.
It seems to lack color. How many color shaders did you use? I think some dark gray, brown and even some black would enhance the craters, all used with some fractal breakup and maybe even some power fractal displacements also attached. I don't know...but, please don't give up...I need some more of your clip files :)
This is just the displacement. It has no color yet. I tried adjusting the gamma for the color shaders used to drive the displacement (to smooth the craters a bit) but I started getting broken terrain. I also lowered the rims.