I would get the red, but I like the red. I love the green, but when the red came out I really ended up liking it much better. It had nothing to do with the Product(Red) thing either, I just like it.
The two main things I'm worried about now are the fact that i will eventually be buying a recording device to record my lectures. I've heard that recordings take a lot of space so that might be a + for the black. Also, like I said before the ER4Ps go so well with a black nano and I would have to paint them or something if I get a red cause I wouldn't be able to stand that Red/White nano with a black headphones.