The ceramics do run cooler, long story ill try to make short. I went to a dyno day with my '04 GTO and there was another '04 GTO there too, on the dyno both GTO's oil dipsticks shot out after doing 3rd gear pulls and when the oil got on my headers (ceramic) it only smoked, and when the oil got on the other GTO's headers (not ceramic) the oil caught fire.
I will definitely be ordering ceramic coated headers when I get to that stage of my build. Hope that helped