That might not even be a good advantage depending on how you look at it. By the time you tackle NYMH you've probably played the game between 2 to 4 times in free aim mode. You've grown skilled at popping headshots and that is vital for killing the Cracha Preto and UFE enemies.
Put soft lock in there and all of a sudden the later chapters become way harder than they should be. You start pumping lead into their bullet-sponge chests instead of getting headshots.