Thanks for the thoughtful review and additional 100% crops. It looks a very good safari lens. I bought a 70-200 f/4 IS for a safari trip just before the f/2.8 II and the 70-300 L. I'm holding on to it because it is so sharp and small. If I was doing it again maybe I would get the 70-300L.
5D IV, 5DS R, 7D II, EOS-M, Powershot G3 X, 400mm DO II, 300/2.8 II, 1.4xTC III, 2xTC III, EF 1.8 STM, EF 70-200/4 IS, EF 24-105, 15-85, 100-400 II, Sigma 10-20, Sigma 150-600mm C, EOS-M5 15-45, f/2 22, 11-22, Samyang 8mm f/2.8 fisheye