The Carbon / Kevlar fabrics are "billed" as addressing some of the weaknesses of Carbon alone. CF is stiff, compared to other fabrics, but also has low impact resistance. Typically requiring a layer of 4 oz e glass over the top to help. CF is also most typically offered as a 6 oz fabric, so in combination with a 4 oz e-glass a single layer of CF becomes 10 oz. If the laminate stack were originally 3 - 10 oz layers of fiberglass, replacing that with a single layer of 6 oz CF and a single layer of 4 oz e glass would result in substantial weight savings. Not so much if the replaced laminate stack is double 4 oz e glass.
Kevlar has superior impact resistance and tends to be the lightest fabric based on thickness. The design of this hybrid is to combine the stiffness of Carbon with the impact resistance of Kevlar in a single fabric. Often times in composites, a layer of Kevlar and then another layer of Carbon was used to achieve this combination, but with a weight penalty.
Kevlar has a few shortcomings, one is that it is almost unworkable in hand lay ups as it requires special cutting and doesn't sand. Another is that it rapidly degrades when exposed to UV.
I've laminated the deck with an translucent UV inhibitor in the epoxy, hopefully the Kevlar doesn't turn to junk!