There's no simple answer to a question like this. Too many variables to consider.
Primarily, the answer depends on three things: 1.) What kind of person you are, 2.) what kind of person he is and 3.) where do you want this relationship to go? Are you the kind of person that can handle a sexual relationship without becoming emotionally attached? Is he? If you do become attached and things don't work out, will you be able to handle the way this upsets your living situation? Is your attraction to him more than just sexual and is he someone you could see boyfriend potential in?
These are all factors that you need to consider when you make your decisions about how to navigate this relationship. Be honest with yourself about what you want and make up your mind, before hand, how you'll handle the consequences of your actions if things don't work out the way you'd like them to.
Me, for instance? I'm a master at compartmentalizing. It wouldn't trouble me in the slightest to have a sexy roommate who spent 90% of his free time with my cock balls-deep in his ass and then to turn right around on a dime and be like, "Hey, you ate one of my yogurts! You owe me $1.17, you bitch."
:wink: