I have size 10 feet. I own 2 pairs of coach mules, huge ones. They're true to size, and I agree with the narrow comment, but I have narrow feet so I'm good. Mine are super comfy. One is a 9.5 and the other is a 10. They feel the same to me more or less, the 10 has a hair wiggle room accross the arch where the fur is (I have the Idyle mules in brown and black.) I LOVE my shoes. Perfect, beautiful, well made.
I do love your flats you picked. I wish I could wear those type, but I can't wear a shallow shoe (you know, the kind that has toe cleavage)
Is there a store near you where you can go give them a walk-about?