A posting above reminds me of a perfect example in Blade Weight. The AH-1S had the 540 Rotor system with the old and heavy blades and was then modified for the Kaman Blades. The difference was such that it was extremely important to know that difference in an emergency. Example a 6" cross section of the old blade weighed, I dont know, maybe 15 lbs., wheras the newer Kaman blade, same cross section was only a couple of pounds. That as an example of total weight reduction.
Difference in flight was like night and day for emergencies. Power off with the heavier blade, slow rotor decay, with the new light one, needle is going down right now. It became very interesting.