I've got ceramic equal-length shorties on my car... would I pay big ammounts to have it done? probably not, but I got my coating for free, so I figured that I might as well because it couldn't hurt.
They say that the ceramic coating helps to keep some heat out of the engine bay - I'm sure it does a little bit, but it's not like you're going to notice a massive difference..... also, unless you're getting the inside of the headers coated as well, it's not really worth your time IMO.
The biggest thing is that I've noticed that the headers cool faster after turning the engine off - not a big deal usually, but it is a bit of a bonus if you're wanting to work on something close to them.