If you look at the TTI books they offer Ceramic Coated, Ceramic Coated with thermal barrier on the inside, polished and black ceramic. NOBODY orders just the plain ceramic and most opt for the Ceramic with thermal barrier. It gives the cleaner look while also reducing heat under hood. The heat stays in the pipe and if you remember you high school science class the hotter the gas, the faster it flows. So if you are coating go for the inside and out. Interesting concept about the rust being sucked back in the engine, but I am sure he found evidence of it.
Todd