I suspected the O-ring would irritate me after a while too, but it was hard to tell since it wouldn't stay on my foot!
Whenever I try wide widths, they never feel wide. Sometimes they feel even narrower than a medium. If you look at the reviews for a lot of Sofft shoes, they will be reviewed as "narrower than marked." I think they deliberately make the wide fit like a medium, medium fit like a narrow, etc. Why they do this is a mystery to me, but it seems like a common practice among all brands that offer a wide width.
Of course, I need a double wide (probably a triple wide if it existed). But those fall off my narrow heels. I own these flats and they were even more painful than my regular width ones.
http://www.zappos.com/n/p/dp/44225196/c/72.html
Besides slipping off my foot, the top of the shoe cut into my "bunion bone" (I don't know what it's called, but it's right where the big toe joins the foot, where you would get a bunion) and I was bleeding and bruised in that spot. It hurt so much that I actually considered taking it off and walking barefoot on the streets of NY! With some careful limping and a box of emergency bandaids, I managed to make it to the train and get home, but it was horrible...especially since I was wearing them to a followup job interview! I had to hide my immense pain from everyone. Not an experience I would like to repeat!