Wayne,

You could one time remove all the spi hardware from your boat and race the A's like that. This could be very telling. I don't except you to gain much upwind, at least not to enough to become competitive with the A's there. On the downwind I predict you'll miss the spi and don't catch up to the leading A's anymore. As such I predict less overall performance then when with the spi setup.

Just an idea to give you a feel of the net benefits or indeed the net performance hits.

Wouter