I've gone through this drill twice now. Both times I used Porsche factory replacement gears. I believe that successful and long lasting repair has less to do with the source of the gears and much more to do with the proper adjustment of the rest of the system as described in DIY section. The electrical relays must be propery adjusted. If they are not the gears will be stripped.
One other suggestion, if you occasionally remove the sunroof. When you are retracting the rear sunroof arms in preparation for removing the sunroof, stop the retraction process just as the arms clear the slots in the roof, do not retract them all the way. If you let them retract all the way, you may end up with stripped gears.
