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i usually keep a single AF point on the eyes, and will toggle to servo when the subject is moving a bit too much. and even then i usually try to get off a few frames. there's no magic bullet in these scenarios, especially if you're shooting REALLY shallow DoF at like f/1.4-f/2 or something.
i'm not sure where the button is on the 6d, but on the 5d3 the DoF preview button can be reprogrammed to be a servo toggle switch, and i can just use my right index finger to switch to servo at the drop of a hat when needed. i bet you can do something like this on the 6d.
re: the image, it's great as others have said. only thing i might suggest is cropping a bit of the dead space off the top. maybe try a 5x7 aspect ratio or something. i feel like there's too much blackness just hanging up there. but other than that it's great.