You might not be saving any weight at all.  Consider that if you compare f6.0 oz fiberglass and 6 oz carbon.  Carbon is about 2/3 the density of fiberglass so for a given ariel weight of 6 oz., the carbon will be thicker and require more resin to fill the interices.  If you were to make the weight of the fabric based on similar strength or Modulus of elasticity, then it would be lighter.  But you should have a much stronger  laminate.

 

One interesting aspect of carbon vs. fiberglass laminates is that the matrix resin often used on older structures like boats, used cheap orthopthalic resin with a strain to failure of only around 3% while the glass had a strain to failure of 5-6%.  So the structure would never actually get to the calculated values if you just looked at the glass since the resin would fail at about half the strain of the strong stuff holding it together.  Ironically, carbon is much better suited (at least in that one area) for cheap resin!  So the lesson of this is the matrix resin should ALWAYS have a higher strain to failure than the reinforcing.

 

Dan