I wear a 9F(EEE) in a Nick's Hot Shot hand built work boot (on par with, some say better than, the White's Smokejumper boot). I wear a 9EEEE when wearing a New Balance running type sneaker. In the Sidi Dominator or Genius shoe, I wear the 43 Mega (Wide), and I LOVE them. The velcro straps don't completely overlap, but I've never had them come undone, and my foot just slips in the shoe like Cinderella's glass slipper, so I don't really worry too much about the straps.
What I'm saying is, is that the Mega is perfect for those if us bicyclists with wide feet. If my foot were only a C in width, I wouldn't be getting the Mega.