Cerakote is nice stuff. If you don't know the guy doing it and haven't seen his work go with the least expensive thing first.
Probably the shotgun, then check out the results. I mean if JLA isn't doing it. I would trust him or jack404 or someone like that on the forum that has been around. If they say they can do it I would believe them. If they have 2 posts...well, you know.