How durable , long lasting are the ceramic coatings on hedders ?
Another thing ceramic coaters generally don't tell you is to be sure to use stainless hardware not only on your headers but on your valve covers above them ... any resulting drippy rust will NOT be covered by your warranty.
A good high temp ceramic coating job should last for many years. Some places do not coat the insides of the tubes though so make sure you know who you're dealing with and getting exactly what you want.
Presuming the next question, I got out of the high temp ceramics a couple years ago, sorry. The shipping costs were just too prohibitive for my customers.