I'm the same as Brad .. with a possible difference in that I'll be thrown around in my incapable 4WD on those pot holed side tracks.
I hate the main roads, and only use them because I have too, or I want to get back quickly.

The other point about most mirrorless(apart from the Sony A7's potential) .. is for something like wider angle(FOV) with shallow DOF.

My main pet hate of smaller formats is and has always been a loss of subject separation for many fields of view. About the only FOV equivalent you can achieve a similarly shallow DOF is the 50-ish mm FOV, where some lens makers offer a fast ish aperture 25mm lens.

A major premise of a smaller camera system, which may or may not also include a smaller sensor is that the the system is small.
If you attempt to create a lens with a similar FOV + equally capable shallow DOF, you just end up with a huge lens, on a small body! .. thus missing the entire point of the small size of the system to begin with.

ps. you don't need to do sports photography to see the benefit of the speedy focus acquisition times that a SLR system is capable of.
Any situation(sports included) will benefit from speedier AF reaction. Some need it more than others. Others don't really care too much.

As for the driver .. no matter which vehicle they drive(small sensor mirrorless, or large sensor DSLR) .. there are technical points that simply can't be ignored.
Equally good drivers exist in all forms of photography .. as well as equally bad drivers, I guess.

As for the Sony A7 .. again mentioned in my reply above too .. while it is a large sensor format compact camera, it's problem is a distinct lack of lenses which allow for technical equality at least in one sense.

Speed of AF will eventually come to mirrorless cameras too. Apparently they're getting better and better with every iteration of model. In short time they will have at least caught up to SLR type AF systems(if SLR AF systems stagnate).

ps. I don't think the die hard DSLR user simply argues against change. I consider myself a die hard SLR type users.
I don't like change for the sake of change .. change HAS to bring with it only advantages. For me(or more accurately to my eyes) the EVF screen is a backward step to usability as of current technology levels.
When the first EVF/mirrorless type system came to market, I was probably the first to wax lyrically for it's potential to change the way we use the camera.
Liveview did that for me actually .. but I've yet to see any EVF that offers a better alternative to a well made and setup OVF.