Totally agree with the past feelings thing. The way I see it, the only time you'll be friends is when the breakup is very amicable, which I feel in most cases doesn't happen. However, first time for everything, I just stopped dating a girl, and we literally broke things off when they were going well. Hooked up again once afterwards, and now things are well. I just went over to her house yesterday to watch movies, and nothing happened (although it might have had I pushed it).
The way it is is thatif you've done it before together, the likelihood of you guys doing it again is that much greater, even though she might not think it's a good idea.