For what it's worth, I'm 6'6" and purchased the Rad City 5+ high step.  The step through was way too short for my height.  With the high step and the stock seat post in its max extended position, I'm probably an inch short of being in the perfect fully extended position.  Considering getting a longer seat post but after 60+ miles I'm not sure it is necessary.  It's a very comfortable ride for my size.