The brake dust sticks to the satin finish more versus the gloss or semi-gloss finish (probably would be worse for a completely matte finish). Also, the black finish looks dirtier sooner than the gunmetal, so needs cleaning more often.
I've noticed on my wheels that the black gloss powder coat looks fantastic when clean and waxed but quickly dulls with a coat of road/brake dust and shows scratches far easier than te OEM silver which as we all know, is the best colour for hiding scratches and swirls. :roll: