Oh, definitely. Should give you a nice boost to plow through that mode. Although it won't really start to be challenging until maybe around the G-Corporation areas. There's a level called "Nightmare Train" that's the hardest, but I think you have to clear the story mode once and play on a harder difficulty to access it.
Never did finish the story mode. Lost interest after I just grinded a bit to get some money and custom parts to use towards character customization for the regular game.