I have found similar data suggesting that in order to achieve a significant weight savings with Carbon you would need to go to cloth weight that is the THINNER than the glass weight you originally specced. With these lightweight laminates you need to control resin weight which is partially done by keeping the fiber thickness to a minimum (thicker fibers need a thicker coat of resin to wet out). This would provide a laminate that is slightly stiffer and about the same weight.
Couple of thoughts I have had: have you considered using slightly thicker strips?? 5mm or even 6mm?? Remember stiffness goes up exponentially with the thickness of the panel. One of the reasons a Marstrom T is so stiff is that they use a 10mm core thickness. I would consider: 6mm thick strips with 200 gsm S-glass on the outside layed with the fibers at +45/-45 and then a lighter 100-130 gsm inside laminate of either Kevlar or tightweave glass (4-Harness or 8-Harness). I think you could get close to the minimum weight, gaining maybe 4 lbs. per hull doing this. You could even try to make up for it by making carbon rudder stocks and carbon beams.
