I bought the regular zip backs and they were too narrow for my calves. I have ordered both wide and regular calve circumference Fryes and they have been fine. But the Melissa's were definitely snug. And they were snug in the actually sizing as well where I would have probably gone a half size up.
I have narrow calves and have a very hard time finding boots to fit. The Melissa's are one of the few that actually fit me. If your calves are on the wider side, I would order the wide calf version.