I have the big one, and it sucks for fine detail stuff (would be great for large flat surface stuff, but not for wheels with detail)...I haven't tried the powerball mini yet
I had the big one and tried it on the wheels. Missed the corners and tight surfaces. Now I have both. The small one on extender (handhold) works great on the 05 Adrenalin chrome wheels.
I have both the big and the small one (I mainly use the small one).
On my rims I apply chrome polish by hand and use the powerball mini to remove it. Because of all the crevices in my rims i do have to go in with a terry towel after and get the remaining polish but I love the power ball. It works great.