Well...both! The Iron Age certainly incorporates both ideas, and it's a struggle that "Cold Steel Wardens" openly embraces. While many of the inspirations for "Cold Steel Wardens" involve heroes without super-powers (Batman, Rorschach/NiteOwl, etc), there are a ton of great Iron Age heroes and storylines focusing on powers, and "CSW" doesn't skimp on including these.
Your humble author has a great fondness for "Rise of the Midnight Sons" and "Maximum Carnage"--both of which feature supernaturally powered heroes (Ghost Rider, Blade, Morbius the Living Vampire) or classic comics characters in new, challenging situations (Spider-Man). That's to say nothing of my fondness for Gambit and the punk-hairdo-era Storm.
It's among our fundamental design goals to ensure that players can built great, archetypal characters and be effective investigators and crimefighters regardless of whether they have powers or not. While their methods may change, the core themes of the Iron Age--brutal combat, intense investigations, social and philosophical issues--all remain!