I soloed NF from up there last night and he didn't come out until I shot the legionary I had left alive. It's definitely quicker than under the stairs but much, much more risky. I lost all my health a number of times when he was at the other end or at the side. They can shoot you! Who'd have thunk it? Fun though as a lot of the time you can't see anything as you are in a constant rocket explosion.