My 2 cents:
I had ordered new headers and had them coated by JetHot, (as my original rear header cracked,) with the "chrome looking" ceramic coating. This was back in March of 2010 at 26,500 miles on the odometer. Now at 42,000 there is no discoloration at all on the front or rear pipe but the coating does look a bit different. Right were you would expect the most bluing/discoloration the finish looks a little flat. Like flat aluminum. As you move away from the "hot spot" the coating goes back to the original, brighter finish. I don't care about it, but just noting it. It could be surface oxidation just from the atmosphere, but I haven't attempted to try and clean it and I probably won't. I went with the ceramic coating to try and reduce the heat stress on the funky Y-pipe on the rear header. I will say that there are a few blue spots on my V&H Ovals, right where the exhaust pipe mounts to muffler. So, the ceramic coating definitely sends more heat back through the exhaust pipe. This did not happen with the original, non-coated headers.
I am a big fan of the ceramic coating and would definitely do it again. JetHot was great to work with and they often have discounts.