Cycles renderer, as implemented is coming along fine, and I feel that in most cases it can easily replace Legacy renderer, but one. I’ve found that bumpmapping is not large deep enough for outdoor environments. I feel that the ability to have a deep bumpmap is handy for doing more-realistic terrain.
Having such bumpmaps may also be used to keep cityscapes manageable while making them realistic. Entire building facades can receive simulate light effects with the addition of a simple bumpmap. I would guess that presently, in the current bumpmap is limited to 2"-4" or about 50mm-100mm, perhaps less.
I also did a test, in which I found that Legacy renderer could do a deep enough bumpmap to make nice water, but Cycles, currently can not. I feel that having this bumpmap capability may help keep people who make boats and ships in Rhino. In my test, I found that a simple texture can make a pleasing water effect, where a 34 million triangles barely equals it. It also took quite some means to create a manageable mesh, created from block’ed submeshes.
Photoshop can use 16-bit grayscale images, but not everyone would be comfortable using them.
[Let’s see… In the same drawing, I have paint-streaks which are about .0625" or even .03125" * 255, would be only 7.968" , so 8-bits would be exhausted with a linear scale, if trying to do 12" of perceived bump.]
[In Quake 1,2, the walls were made about 16 inches/units to avoid z-fighting/HOM, from shallow z-buffer sorting depth available on the early GPUs. It wasn’t an esthetic thing : ) ]