I'm on the second iteration of the heel flap. I tried doing just a 5 x 2 rib, but it looked stupid (fortunately I realized that only a few rows in). I hadn't wanted to do the eyelets down the heel flap because I was worried about my heels rubbing.
One problem with that line of thinking, I wear clogs 85% of the time. Eyelets down the heel it is!