I'll take the superhero aspect over the sci-fi any day. Too much sci-fi influence can get kind of boring since it always seems to lead to a lot of ill explained techno-babble like all that terrorform gibberish. Or you get ideas like the Thresholds, which would fundamentally change the fabric of life in the galaxy but whose implications can't be fully explored because the book inevitably will bend it's way back to colorful people beating on each other.
To me, stories that focus on the Legionnaires as people first and heroes second are usually those that remain engaging after many years pass.