I run a small Company that has done helicopter engineering for 23 years and though we haven't delved into main rotor blade development, we have tested new tail rotor blades for the 205/UH-1 series. I can tell you that it was a mess. Unless one clones the exact MRB design, including airfoil profile, weight distribution, and construction, the development effort and costs will be horrible. Even if the blades are lighter, stronger, cheaper to build, the dynamics, proof of service life, and aerodynamics will eat significant dollars. Just for one example among several, consider what the lighter blades will do to autorotation performance and the H-V chart.