i have found this script by Vicente Soler ( [http://www.grasshopper3d.com/forum/topics/how-to-render-mesh-colors?commentId=2985220%3AComment%3A66338 ) exploded the mesh, averaged the color and baked .
usign Keyshot latest update of the “bridge” link from rhino to keyshot the transform was smooth.
hope this helps someone.
cheers