Unless I am doing something very wrong (quite possible), it is my understanding that if you have a fully rendered keyshot model and you need to make a change to the solid model, you basically need to do most of the keyshot steps all over again. It would be nice to somehow retain all the settings in the model and only need to reapply material/color/etc. to faces that changed between iterations. Re-applying materials/colors is a big time waster.
Perhaps even a simple "replace" function, so you can replace the current model with a new model, and the software just determines which faces are identical from old->new and keeps color, material, etc. settings for them. Or even by solid body.
Coming in KS4.