Brigit, I use both methods of binding and generally find that the self bound quilts finish faster. I do not neccessarily leave as much as everyone is posting. I generally want a 1" binding so I leave 2" all the way around and turn to the edge of my top. I then turn again to stitch.
I have found that the mitered corners are easier on a self-bound quilt rather than the tradional binding. I turn the corners in toward the quilt top and tuck under. This forms the miter when folded in twice. As long as the "binding" is even on all sides, this will make a beautiful miter.
I do sell my quilts and have not had anyone hesitant because it was self bound.
As many have stated, this is a matter of preference and you will need to decide.
Good luck with however you chose to go forward with this.
from Western New York