My god man, I think you've captured the essence of this beast.
Other than what has already been noted, the primered areas, metal surfaces, etc......
My preference for worn metal is as follows. Use a simple #2 pencil (very last) for freshly worn metal, it's simple and effective; just don't spray any flattening or gloss coat over it....it'll ruin the effect.
Now I'm thinking Tiger, Tiger, TIGER.