You can try a different pad with the #9 and compare results. If nothing else it will be a good learning experience. Every paint job reacts differently to products and application techniques. A PC lets you experiment and learn while keeping the risk of paint damage low.
Do a search for 3M products here at Autopia. Lots of conversations about various polishing products have taken place.
Always try a different combo using stuff you have before running out and spending $10 on another product that may or may not work. Even if you have a product that you think is too aggressive, mix it with a milder product and test results. The best detailers I've ever met always had their own little concoctions of mixed products to do a specific job on a specific problem area. Some guys I know had custom mixed products just for certain types of cars (Lexus is know for their hard paint, Porsche for their soft paint. The same products will perform very differently on those two cars).