Re: Krylon vs. duracoat
If the metal surface is not prepped properly (120 grit Aluminum Oxide blast), the Ceracoat will chip off just as fast as any other finish without a properly prepped base. Ceracoat is "pickier" than other finishes and is harder to apply unless everything is good.
Duracoat I have applied on surfaces sanded with 400 grit paper and steel wool and turned out fine, albeit not as good as another project that was aluminum oxide blasted. Either way it will be better than Krylon, but you must pay attention to close fitting parts as Duracoat goes on thick.
If you have limited means of prepping the surface right, go Alumihide II (degrease, heat part, then spray), or stick with Krylon and reapply as needed.