I remember a guy who was restoring his MKI Golf on Detailing World, he wanted to get the OEM look on the brake calipers and other engine parts, he ended up mixing both silver and gold Hammerite (can't remember the ratio though). The finished result was an OEM look and looked really good.
When I get the time, I'll be doing the same to my calipers and painting up the disk "top hats" and edges in silver.
If you have decent big brakes then red, purple (choose your own colour and enter here) works, if you have standard brakes like me, I reckon an OEM finish looks tidy.
Just my tuppence worth (runs off to Detailing World to search for the restoration post....).