I went optimistic and said 3-4 as well. I remember when the Nats went to Cincy in 2005 and got their heads handed to them. When a team that can't score runs plays a team that can, things can get ugly. And since the Nats have a patchwork rotation, I'm afraid that at least one game will go to the Reds in a demoralizingly big way.
I am hoping Cincy's pitching (especially in relief) stays bad enough to give the Nats chances to win two games late, and that the Nats convert at least one.