It will be very individual. Some feel a light board is nothing special, others almost get mesmerized by low weight. The same goes for flex characteristics which also differ between the three constructions. In pure performance terms, the competence of the sailor will affect speed, planing and such things much more than the construction. I personally feel that with a light board you tend to get more active and work the board more (at least initially). So you get a positive psychological effect.
On the Futura, I think you will probably feel a bit of an extra edge of wood in really light wind, when you're pumping and working the board with your feet a lot. And then in high wind, the wood will ultimately take a slight edge of the bumps, making the board feel just that little bit smoother. But if it's worth the extra money I cant say. You have to decide for yourself.