I have a mini ex, and a tractor, I use them both for what they're intended for. The mini ex is great for making roads, less good at grading and maintaining them. A cheating trick which works for grading and crowning with a mini ex is to get a bucket full, then swing the bucket all the way out, to load that side of the machine a little more, it'll crown a little that way.
My best success for grading was finding an old (1920) Adams horse drawn grader ( no horses came with it). The front wheel carriage was missing, which was perfect. I welded up a fork type trailer hitch for it, but instead put a three point draw bar in there. I hook it to the threepoint lift arms, so I can fine adjust the grading height as I go. I put a hydraulic cylinder on one blade lift arm, so I can use my accessory valve to adjust the crown as I go. The huge spoked steel wheels look out of place, but work really well.
I prefer having a separate mini ex to a backhoe on the tractor. So when I get one stuck, I have the other to pull it out with. And a mini ex is much faster for ditching than a back hoe, ditch on one side, load your trailer (drawn by your tractor) on the other. backhoes are poor at that (unless you have two tractors). But, the backhoe will drive to the jobsite faster!
Before you buy a mini ex, try it first. In particular, judge how powerful it is. I have a JD15, which is a powerful machine for its size. I have run others, which were bigger, but less powerful (breakout force, and lifting). Size of machine may not be proportional to power.