I have both the Daytona and Jr. brushes. The bristles are too wide and the brush gets stuck between the rim barrel and the aluminum cover (~1" width) before the brush reaches the back of the rim. The Daytona's worked ok on our other bimmers but I can't get to the back half of the rim barrel with the new car.
I used a long thin spoke brush with natural tampico bristles for years until the car parts shop in town went out of business. They were only about $5 and worked great with the cross spoke rims that I still have on our '99 528iT wagon. I'm not sure where to buy them now.
I was also thinking about the RaceGlace brush as Al mentioned but I'm not sure if the width of the bristles will be a problem too.