Would knowing the truth be a turn off or endearing?

If the topic comes up, don't lie about your childhood. You don't have to tell every detail, but you can explain that you struggled and that you overcame difficult cirstances with your parents and their financial situation. He won't think less of you. I can completely relate because I also had a very abusive childhood, but I present the image of someone who is "put together." The guys I have told about my life respect me more for being strong enough to overcome my situation. I suspect your guy will admire you even more too, and will feel closer to you because he will know a bit about the real you and your life.