Stiff-soled boots are really, really bad for the calves. And the knees. And the hips. And the feet. And the back.
Basically, they're gonna hurt. I simply can't wear them, on order of my physiotherapist (I have a minor back problem). He also says that even for people who don't find them a problem, they're making problems that will affect them in later life. Your feet and ankles need to flex.
Obviously, the choice is yours though