I got around the same results, apparently there's not much consistency between LEDs from the same reel. Your LEDs actually were 1 chain of 36 emitters which I had to cut in 4 for shipping. I have 10 of these R2's myself and my readings at 350mA go from 3.22V to 3.57V.
I wonder how this comes. When the first Q5's were released there was the problem of extremely high Vf's, although Cree added a bond wire which should lower the Vf, especially at high currents. I remember the good old days when P4 was the highest flux bin, but Vf readings were very constant AND low (I remember I tested 10 P4's at 350mA going from 3.15V to 3.22V). Apparently the extra bond wire didn't help that much... I suppose there's some other change which increases the Vf?
Even though the Vf's are not very consistent on these R2's, I really love them. Compared to the P4 they give a huge brightness boost and even compared to Q5's they look brighter to the naked eye. Fortunately my light meter is back on it's way to me so I can take measurements
Cheers to you, Mac! And happy modding with these R2's