The owner of Diamond bows told me (during our only conversation) that the measured brace height can be deceiving as some bows string will travel further past the starting point than others during the shooting cycle. That's not verbatum (sp?), but by the end of the conversation I knew what he was getting at.
With 2 bows of equal brace height one could slap your wrist when the other does not.
Me personally, I would start with a bow with at least 7" and go up from there. Some manufactures offer bows with 8" brace height and above 300 IBO speed. Diamond and Renagade both have one.