Hey Tom,
I think there is a reason you don't really see it done. Lord knows if it was to look good, you'd see it more often.
Considering the FXCWC was HD's version of a "custom chopper", when you look at custom bikes, most keep the caliper's clean and discrete. Colors being chrome, billet or black. The attention is typically to focus on the wheel/rim.......
Gold may look good if it's been used for other bits to bring on a theme maybe? But, to me it would bring a bit of a dated look. That's just my opinion.