Just curious (I have not looked at controllers in much detail so this is educational for me too), have you experimented with the programming interface for your 7245? You might need to just to see what the under/over voltages are currently. You can also do things like customize throttle response and set the max current to %50 or whatev. But I would agree with daox if you can afford 72v off the bat, just don't wang the throttle open on your very first takeoff
