Is this a turn off for you too and why?

Your right he shouldn't let past relationships interfear with current. But then again does he know that? Tell him calmly how you feel, and tell him that you don't like being compared to his exs. If he does like you he will understand, but don't get too mad at him. Once you've had your first time with him then you will start your own record... and if you ever should break up then he would tell other girls to do it like you lol