I made a workbench with a command that creates a parametric planetary gear system based on my previous macro. So the number of planets and their positions can be updated by just changing the settings in a featurepython object. The planetary gearset made with this command is similar to an assembly from Assembly4 just with a few modifications in order to keep all the objects, links, and expressions inside one part object.
Here is a link to the workbench (note that I am building this workbench on top of the development branch of FCGear in order to create the internal gear). And here is a video showing the parametric planetary gearset in action:
I made this workbench with my own use-case in mind (I want to 3D print a planetary gearset) so it may need some tweaks to make the workbench more useful to other use-cases.