I would say that you should really consider the conditions you ride in, and whether or not it will be affected by plugging in.
I'm a daily commuter in NYC. The route i take is pretty efficient, but has few bike lanes. At one point, i rode with earphones for a couple of months and decided that i didn't like it. I DO hear cars coming (particularly when it rains), and it helps when i'm crossing small streets to know whether or not i can go directly through a light. Riding in the city is never boring, music or not. I feel good about being more aware when i'm riding, because let's face it, neither cars or pedestrians are looking out for cyclists. I like to let other cyclists know I'm listening and aware of them and know that they are aware of me as well.