When I was racing last (cat 3) the cost was higher on road bikes! Don't know if it still is. It is still a preferable setup if you don't need the range of gearing if a double. Front derailleurs are are common point of failure and noise and you make it all go away. (with either the proper sort of front chainring or a clutched derailleur in the rear to make sure the chain stay son)

Drop weight and improve aero a bit too.