Mr. Carnathan certainly loves Canon!
Too bad this lens is sharpest at the wide end. I have a 70-200/2.8 II that fills that need. I was hoping for very sharp at 400mm. The new Sigma is looking better and better.
Just about everyone who has reviewed the Sigma has complained that it is too heavy for hand-held use - not only is it heavy but the heaviest part, the front lens elements, protrude out very far unbalancing an already heavy lens. The beauty of the Tamron 150-600mm and now even more so the 100-400 II is their portability combined with pretty good IQ.
I wouldn't say they complained that it is too heavy for hand-held use. Actually, they used it hand held and certainly noted its weight. I am one of the few with the 150-600S and have only used it hand held. Sure it is heavy, but I've gotten used to it. It is a heckuva lens. Believe me, I am tempted by the 100-400II because of its size and MFD, but so far I am sticking with the 150-600S.
Bryan's reviews are almost always reflective of my own experiences. If he loves the lens, I have little doubt I would too. My only issue is that I really wanted more reach than 400 mm. So, I am watching the IQ and the AF performance of the 100-400II +1.4TC. But all that time, I am shooting and liking the 150-600S more and more.