You might check out this Sharon Schamber binding video. Her directions for the corners have worked great for me. If you clip the quilt in the corner, it seems to me you'd have empty binding in that area, which you don't want. When I've had problems with the miters not lining up neatly, it's been because my seam allowance there was a little too wide.
https://www.youtube.com/watch?v=a2hWQ5-ZccE