I'd be interested if someone did a test for radius of soft shadows as it effects render time. Actually, that's something that bugs me about every 3d application I've used. There's no chart at the back showing the basic structure of the algos, giving the ray depth and any other hard numbers they can generate. Is up to end-users to set up physics labs and light labs and post their results at BBS's. I happen to like skylight a lot, and use that instead of multiple lights when I can. Skylight gives a wonderfully soft affect without the flattening of ambience.