What a great picture from that 100% crop. I read and watched many reviews of which most said the same things you just said. I don't know if different copies made at different times have changed but when I got to the location and was testing my rental copy of the Canon and Sigma was there letting people try for fee I did jump at the chance of testing and seeing real world differences. I was fully expecting to get back home and see great images from both but more from the Canon. My thoughts were that the Sigma wouldn't hold up when cropped if they were sharp at all. What I got was more hits (keepers) from the Sigma that were equal if not better in sharpness (even at 600) with better bokeh performance to boot. I fell in love with the images I got and at that point I could no longer justify spending the money on the Canon. It could have just been the confluence of a bunch of different things coming together to make the Sigma shine but now that I've had it for a month I don't think it was.
The only issue I had with keeper rates was when I was taking pictures of shore birds two weeks ago and the sea breeze was high. I shoot hand held and holding that bad boy still even at fast shutters was difficult at best. I got some great shots but not near the keeper rate I have already become accustomed to. The smaller lighter Canon might have done a better job for me that day.
I have heard the Tamron is softer between the 500-600 range but I have not even seen one of those to even think of trying it. I did purchase this knowing my limitiations was pretty much outdoors only but that is why I bought it.
Canon 7D Mk II, Sigma 150-600 C, Canon 70-200L 2.8 Mk1, Canon 24-105L Mk1, Canon EF-S 10-18 IS STM, Canon 50 1.8 STM, Canon 24 2.8
