Thanks for the input, everyone! More or less, from everything people have said here, I've come to the conclusion that given my riding style (like I said, I ride pretty conservatively) and the fact that Boston is pretty flat, I should be fine with just a front brake.

And Carleton, thanks for the input - I appreciate that you seem to be concerned for my well-being, but I'm not going to be going crazy or racing any time soon, so I think that I'm up for the challenge Like everyone's said here, I'll just have to work my way up. Thanks again!