I suppose that header coating are only as good as the company doing the job. I have had 3 sets of headers coating by 2 different local companies in British Columbia Canada. The first set was a pair of custom headers that TomP built for my FE Fairmont about 20 years ago. Those headers were 8 separate tubes and 2 collectors, so you would think they should have been easy to coat, since every tube was totally accessable, but they started to get rust pits after a few years, and the collectors, which admittedly were older, as they had been also used on my previous headers, ended up paper thin. like an aluminum Coke can, and split. Later on, I had a pair of FlowTech long tubes for my 85 Mustang 5.0 Stocker, down at the other company , and 5 years later, they still look like new. Both sets were done with the shiny, almost chrome looking finish, and were just used on race cars.
About 7 years ago, I bought a new set of FPA bare steel headers for the 428CJ in my 59, and after making certain they fit the car properly first (which they did), I had them coated, in a mat gray finish, at the same place that did the FlowTechs. They have now been on the car for 4 or 5 years now, although I have only had the car on the road for a year now. I have driven the car about 3000 miles now, and they look just as good now as they did when I first installed them. I also had another set of custom made FE Fox body multi piece headers that I bought from a Super Stock racer from Virginia. They were coated by Jet Hot Coatings, and they still look pretty good for being over 10 years old.
Personally, I prefer to buy the headers bare, and have them ceramic coated, only after I have tried them in the car, to ensure they fir properly. The last thing I would want to do is to have to modify or dent any tubes that have already been coated.