Against a Dark Background and The Algebraist (and possibly even Transition, if you go in for the Many Worlds) are Banks titles that are harder, if not hard boiled. Banks overall is certainly a more literary writer, though, but generally his concern has more to do with the sociological side than with the technological/scientific side. Transition is an interesting one, I think, since if we take it at face value, it's SF, and as far as adhering to theory goes, it's fairly hard. But if we assume the narrator is insane, then it's something different (do we call it "slipstream"?). Arguably one of Banks' best in a long time, IMO.