I purchased these shoes and I just wore them a tiny bit at first and they seemed comfortable.  When I finally got to wear them on some trails they cut into the back of my heal.  The reason these shoes hurt my heal I now understand.  The part where your foot sets is cushioned and the bottom of the shoe that also comes up in the back and joins the cushioned part is very stiff and doesn't give when the cushioning flexes.  I wish I had not waited so long to find this out.  My Teva's don't hurt my feet like these do.