An update: I have used this lens a fair amount and have gotten used to the sloppy MF. I do like the long throw and the AF is dead on with my 5D IV and 80D.
Recently I went back to shooting wildflowers with my Milvus 100 and wondered why the images were not as sharp as usual. I then did a comparison and am surprised that the Sigma is noticeably sharper. I am considering selling the Milvus. I am also wondering when Sigma will offer a 'R' mount conversions.