Focus seemed to be faster when using the center point(s). The corners of the frame rely on the (much) slower contrast-detect focus, and that's what this user was using so it makes sense. How does it do with a regular EF lens when focusing with those center points?
Also, I wonder how tough it would be to get a sharp image particularly since you are forced to hold the camera away from your body, which removes one aid in stabilization. Particularly with longer non-IS lenses (say, 85 1.8 ), probably would need pretty fast shutter speeds, I would take it? Hopefully an EF-M lens in the 60-80 mm range with IS materializes to fill this gap.
Perhaps a EF-M telephoto option (even the EF-S 55-250 looks pretty ridiculous on that tiny camera, haha) might be in the works too, but that wouldn't really matter to me personally anyway.