You are over-thinking this decision. Whether a rack is silver or black has no relationship to its function, durability, defects, etc. It's simply a color. Black components seem to sell better, or perhaps dealers and component manufacturers make more money off them. When I was looking for a rack for my touring bike, I had trouble finding a silver one. I wanted a Tubus Cargo rack but the US dealers only sold black ones, so I had to order my silver one from England. Trust me, it is the same rack as the black ones, just a different color. I also have a black PB KOKO, and it is a great rack for the money.