Mark I am not as harsh as Tony, but I will say in my limited time I have used the mirrorless it is not a replacement for a sports / wildlife camera. I bought this camera for a specific reason - as a back up camera to my 1Dx for static wild life and a lighter rig for when I go hiking in Africa next year.
I needed a second body, and had the choice of investing in a second DSLR or make the move to mirrorless. There are some aspects of this body I really like (the articulated rear screen) and I am not against the EVF. In honesty if time was on my side then I would have waited for the second generation of canon mirrorless, but I wanted to get as much practice in as practically possible before I travelled next year. What made the decision easy for me was the flawless adaptor allowing my existing range of lenses to work on the mirrorless body. I have canon, zeiss and sigma lenses and all seem to work as well if not better on the mirrorless body.
As with the change from SLR to DSLR, I think the future is moving towards mirrorless now that canon has made the move, they will force that move (as that is where most of the newer lenses are being developed).
For the work you are doing I do not see any advantage in moving over to mirrorless just yet - wait for the next generation of bodies, and see if Canon release a crop sensor version (equivalent to the 90D+).