There is no easy answer for this. It is unfortunately hard to advise what are "good" values on the forums, as it's based largely on personal needs, preferences, and judgement. I thought our initial results were pretty good, and there was no point to ultra high. Now that we've improved our technique I know better.

Key to this is having good diffuse lighting, and sharp enough images that the processing will benefit from the full resolution of your images, as opposed to the 1/2 resolution that it uses for high. To get this you need good focusing and/or prime lenses. Sharp sharp sharp.