glemans , welcome to tbn , both have their place . I prefer the box blade for maintaining the parking lot at my store . I don't let it get in bad shape , potholes or to thin without spreading more rock on it .
Welcome,
The general consensus is that a grader plane is the best implement, but a box blade or just a blade can be used well. Not sure if it's different on the BX series but you might check in the Kubota section and the attachments section to ask.
There is a pretty good video on the subject at Everything Attachments.
Tractor Land Plane - Tractor Land Leveler - 3 point Hitch
Tractor Land Plane - Tractor Land Leveler - 3 point Hitch