ceramic headers worth it?

Those look like they have a much smoother finish than the coating I was talking about. Flame sprays have a lot of texture although I suppose one that's mostly metal could be polished smooth. On the set I tried to install on my car (circa 1989) we wrapped them very carefully so as not to scratch the paint on the inner fenders.

For the OP. In terms of heat conduction a zirconium finish should bring steel headers into the same range as stainless. For reducing radiant heat, smooth and shiny, or light colors are usually best but its hard to know how much just by appearance.