[Bumpinjeep]

Here are some things to consider.
1. Brake dust. With brake dust, the caliper will also be coated in it and you will have to wash it when you wash your car, it's an extra step, but something to be aware of. If you don't like taking the time to wash the caliper, go with the black brakes.
2. Clashing. Blue on Blue would be okay if the blues were the same hue. If the two blues were different hues, it would stand out and could drive you crazy depending on how attentive you detail you are.
3. Caliper size. The rear calipers on these cars is embarrassingly small. Like, it literally looks like an afterthought. Almost like they ran out of money and threw in the same caliper off of like a 4 cylinder X1 or something. If you were to choose the Red, it would stand out. Going with black would blend it in.

I personally always liked the look of Red calipers on sports cars. Hell, I even think they look great on my wife's GTI.
Just some food for thought.