An Air Buffer is an excellent tool , but it requires alot of air Volume , and are fairly expensive to boot . I also like the 2 sided wool pad that is used with them .

I also use an air Dynabrade 3" palm buffer for small parts and hard to get to body areas , another expensive tool , but sure beats hand buffing/polishing

If your not using it for everyday dependable usage , I wouldnt purchase an expensive buffer .

I have never had the chance to use one of the smaller Porter-Cable units but look small and light to use .

I dry sand with a 1500 grit on a 6" , then use the 3000 Trizac 3M 6" Da sand paper with a mist of water on the pad , and sand over the 1500 areas, and you can go straight to polish , works like a charm .

If your going to use a foam buffer pad to buff with be careful with them as they build heat fast and have a tendency to burn the paint /clear and can warp hoods , roofs and deck lids , and when they start to dry out from buffing and working the compound they will start to make the buffer hop and skip , so make sure you only work a small area at a time ,a 20" x20" square area is sufficient at a time to keep an eye on the area .