This seems like another interesting topic. I think you really need to look at this in it's entirety, without letting the "ex" factor play into your mind. If this was a guy you did this with that wasn't your ex, would your feelings still be doing in a thousand different ways?
Can you honestly do this type of stuff without setting up expectations or demands that aren't guaranteed to come true? I doubt you can. If you want a friendship with an ex, you need to ensure you can handle things that may occur, like this, without automatically assuming it means a solid future relationship.
I am not going to rule out that you two can't reconnect, have fun and enjoy, but seeing is you have a tumultuous past, one of you are going to have feelings much stronger than the other, and that is when problems occur.