Man, those are some very cool redesigns. There's a lot of history folded into Rafael Grampa's alternate cover of Detective Comics #50. While that armoured Batman is heavily modelled on the one from The Dark Knight Returns, you can also see some small nods to the character's Silver Age look, like how the utility belt has capsules instead of pouches.
The Superman costume features more visual cues from the Man of Steel's history. There's the Silver Age S-shield, yellow piping around the tops of the boots and, my favourite touch, red/yellow highlights at the waist which gestures at both the classic belt-and-briefs combo and the sleeker New 52 version. Gotta love the logo mash-up under the signature on the lower right, too. Great stuff, Rafael!