On some aircraft you may want to shift the CG rearward, on others (F33A) you may want to shift it forward. This would be a major consideration if I would change props for any reason. Since the prop is about as far forward as you can go, even 10lbs difference will have a major effect on CG. On the TN Bonanzas a new composite prop helps compensate for the 70 lbs weight of the turbo installation. One aircraft I fly needed a very large 110 cuft O2 cylinder in the back to compensate the weight of the turbo. With a lighter composite prop this O2 cylinder could have been several sizes smaller, leaving a higher useful load.