Hi, great house. Love the 18th century places. I like the roof color you have, but think green would work great too. Not a fan of black shutters here myself. If you go with a green roof, I would likely to the shutters in the same color if it was me.
The bronze roof you saw, sounds like what a friend has on his, they called it a copper wash(which I guess must means a color designed to make it look like a more expensive copper roof).
Locust Quarter, circa 1770 Georgian Gambrel roofed cottage.