Jim, it almost sounds like you're talking about a fiberglass bow? If so, I have no valuable input. But if it's an all wood laminate... The "core" where the actionboo is...would be less dense & therefore lighter at any given thickness relative to osage at same thickness. Because the center of the bow does so little work, "strength" there is of minimal importance. The strength of the bow is in the tension of the raw bamboo & the compression of the osage belly. Very small changes in the thickness of the osage will make great changes in weight. The Osage belly lam would have to be thicker, yes. But almost imperceptibly so.