Depends.
D&D "Hell", the Nine, Baator, whatever, is much more fire-brimstone-plots-and-schemes. It's about flames, self-corruption, and intelligent evil, a smile and a stab in the back. This means that in the world of D&D, those who lie and decieve, who achieve rank through destroying all goodness, are "hellish," and the beasts from that realm do likewise.
Your theorietical "Metal Hell" is something like a dark industrial nightmare, cold gears and chains grinding, with grays and blues, sizzling and macabre. It's the distant logic of a machine, of neccessity, of weapons and armaments, sacrifices to the grinding links of blood-soaked chain. This means that in a world influenced by that, war itself is hell, the pain and blood are suffering, and those who can wield their power crush those who cannot beneath the sword, or the metal boots of their underlings. Likewise, the devils inspired by this hell would be more visceral than normal, torturous and violent, and not just for their own self-interest. They would rend a victim limb from limb to show that victim that they are indeed nothing more than a cog, and can be discarded if they grow troublesome.
In Eberron, Hell, aparently, is "Eternal Battle with Other Cosmic Forces." And it can just as easily be Heaven, or the Abyss, because they all cause it. Hell is a fort. That's not exactly as inspiring as either metal-hell or D&D hell. It's just kinda "Oh, this is where Devils come from." Devils in Eberron...er....hate....celestials........yeah.........surprise?
