I think that it depends on what you want to use the bike for. Personally I don't feel comfortable riding a carbon fiber fork in the street. I hit too many god damn potholes and end up hoping too many curbs to where I get paranoid doing it. The big prob with carbon fiber IMHO is that it doesn't show any signs of wear before one it just shatters. With steel, if it gets hit badly enough to compromise the integrity of the fork it will be obviously dented.

If you are doing more road riding or are mainly going to be riding on streets without a lot of potholes than I'd go for the langster. Also, the steel langster is ****ing hot!!!!

*disclaimer- happy IRO owner

P.S. Reynolds 520 is exactly the same as the 4130 cro-mo that the IRO is made with