<p>Because you have not visited Carleton yet, there is a chance that you will dislike it after visiting. Even if you like it after Nov 4, you won't regret going to Brown. So, go for Brown ED because that gives you the best shot for being accepted. Do RD everywhere else.
I have two principles:
When in a dilemma, take the safer course of action!
When in a dilemma, trust your gut feelings!</p>