Most shops dislike anything that is labor & time intensive. Production shops turn out some really third-rate work anymore. It pays to know who you're dealing with and what kind of work you can reasonably expect. Epoxy primer is a bastage to work with. HOK in particular is tough to flow-out and even tougher to block sand. On the other hand, a good epoxy primer seals the metal and sticks like white on rice. Nothing like a good solid base for the paint. I'm a firm believer in using a single paint system, from the same manufacturer from primer through clearcoat. After all of the time, work & expense involved with a first-rate paint job, may as well go for max durability. The cost differences are insignificant.