The Sony a6300 + Canon 100-400L lens make a great combo for me to shoot hummingbirds with. Focus is fast using the Metabones IV adapter. I used AF-C mode and wide AF.
Because of the 1.5 crop factor using this camera, the effective focal length with this combination is 600mm with no minimum aperture penalty and the 24.2mp sensor is larger than my Canon 5D3 (22.3mp).
IMAGE LINK: https://flic.kr/p/H1zVEf There's a camera on my lens! by Gene, on Flickr
Most recent example photo.
IMAGE LINK: https://flic.kr/p/LMTT4b High Alert by Gene, on Flickr