To remove grease from a (cold) engine, natural turpentine works well, also good for baked on road tar.
I guess there are two groups of folk responding to this thread: the ones that use their bikes through the winter, and the ones that don't. If you belong to the first group, the fact that there is a waxy protective coating available that saves your brightwork from winter ravages, is a real bonus. There are any number of non-aggresive ways of removing it when Spring comes around.