the H16 spinny pole is very long, this means that the luff of the sail angles up and gives the bow lots of LIFT. I think that the youth guys around me could sail downwind in any wind strength - the problems come at the corners when they slow down! so typically, they can handle top end of a force 5 without too much trouble.
Its a good addition to the boat and i am amazed at how head in the sand the world 16 class is about the spinny kit.
i can go down the garden and measure any bits of my sons 16 spinny kit that you like

Paul