Its true that header wrap is a lot cheaper than ceramic coating, but the coating shop i have used in the past offers a lifetime warranty on their coatings.
http://.www.finishlinecoatings.com Tested by NW racers and proven on the Bonneville salt flats.
Show me one single exhaust manufacturer that will honor their warranty with a header wrap, None i am aware of. Look up any of the Auto exhaust company's and most clearly state that warranty is voided by using wraps. The exhaust system im buying for my wifes 69 Chevelle isnt cheap. NASCAR teams figured this out as well. wraps were very popular for a short period of time and they found they were replacing exhausts too often, a custom made race car exhaust costs thousands of dollars. Hot Rod magazine, Car Craft magazine, Super Chevy Magazine ALL Had articles about the problems with exhaust wraps and the deterioration it causes. (I guess they failed to check with you guys, instead they consulted metallurgy engineers and race car builders)
The mileages you guys are quoting is a reflection of the quality of the part thats endured, Not a endorsement of wraps.
Its simple physics and logic. Metals that are wrapped cant dissipate the heat, the more heat, the quicker they break down. Study's show linear metal erosion based on temperatures.
A ceramic coating properly done, coats the inside and outside, Heat doesn't absorb into the metal, it flows out the end,Which scavenges the combustion chamber resulting in a power increase. While a wrap might insulate surrounding parts from the heat, so does Ceramic coatings, but without the damage to the pipes.
Physics, not just a good idea, its actually the law. Another way of looking at this might be what my Instructor once asked me in Aviation mechanics school, I had rebuilt the ignition system in a 18 cylinder radial Aircraft engine, I was very proud of myself. But he asked me "Does it run BECAUSE of you, or in SPITE of you?"
YRMV (Your Results May Vary)