I really like Perlman as Hellboy, but he ain't getting any younger. I can see Harbour being really great in the role actually. He's got pretty much the perfect "style" as an actor - very low-key/cynical/sardonic - for Hellboy. I hope the R rating doesn't indicate a move in the "grimdark" direction though. As much as there's a lot of horror and death in Hellboy, there's an underlying humor that is critical to the title afaic.