The Planetary Surface Shader is still in a bit of an experimental state. It's not terribly versatile or compatible with other shaders and is really best for simple planet effects and little more. Although it takes a lot more effort, you can achieve more realistic and most of all versatile and powerful effects with the built-in surface mapping ("Shaders") system, including full continents and mountain chains and sophisticated displacement handling and surface distribution. Experimentation is of course encouraged but for now if you want anything beyond the basic effect the Planetary Surface Shader provides, you're probably best just creating your own setup through the Shaders.
- Oshyan