I just got one a couple months ago. Didn't know 72" MMM was an option. I have the 60". I can cut full speed in high range on normal lawn grass without much issue. For such a small tractor it sure does a lot of work! Rear ballast is your friend using the loader. I usually keep my rotary cutter hooked up and it still seems a little light in the back end. You will probably be fine if the backhoe is hoked up. Although be careful as I'm sure a lot of that weight is up high.
I really want to try a 5' rotary cutter on it. I'm sure it would have plenty of power but I'm not sure about keeping the front tires on the ground.