Dont know if any ones used them but EBC perfomance brake pads are quoted as dust free. They come in green or red, the red beeing a very hard compound and designed for racing, I know they do them for the R170 but not sure about the R171.
http://www.ebcbrakesdirect.com/car/p...E3+%2897%2D%29
I find the best way of keeping the rims clean is to remove them monthly wash and polish, as the polish stops the dust sticking as much.