Jerry, I think there are only two different rotors: the early type with the flange, and the later type without the flange. My K1 with the flange weighed about 5.8 pounds, and the K7 rotor without the flange that I'm using now weighs about 4.6 pounds. Almost 1/2 pound more can be removed from the late rotor without losing any charging capabilities, but the RC claims of removing 3 or 4 pounds off even the heavier 5.8 pound rotor and still having any charging at all are way off.
Your pic from the last time this came up shows an early rotor on the left, and two modified rotors on the right; neither is the stock late rotor. As far as when did they start, does your F0 have the early rotor or the late style?