I mean Rorschach doesn't have a no kill rule, doesn't have a strong connection to his parents, never traveled across the world learning how to be good at everything, isn't rich, doesn't have a roster of villains, has a different personality, isn't based in a gothic hellhole like Gotham, and doesn't have countless storylines to adapt. The only thing that'd be similar is that they are insane, and most Batman depictions already make him slightly insane (Batman: Imposter is a recent one which delves into his sanity).