Quote - I did some renders this evening with a white ball, (color 1) without any textures, with a single spotlight and IBL . Poserpro GC makes the diffuse shadows and highlights on the ball very hard, and I don't like that, but perhaps I'm doing something wrong.

 

   You're doing nothing wrong. This is how real light behaves. This is a real life sphere with a point light, and the line between light and shadow is very harsh. It only looks odd to us because we rarely see any object lit from a single direction, there is almost always indirect light in addition.