Those pictures are great. Thank you for the time you put in taking and posting those pictures. That is very similar work to what I will be doing with tree prunings and smaller branches. I am thinking the 72" with 9 tines would be a good match for that. Yet I also have a tremendous amount of heavy logs and brush to move also, like your last picture shows.
Your tractor is a lot heavier than mine. My tractor, although 50 gross HP, is under 4000lbs (before loader). Tires are not loaded. Even with boxblade on back, I am concerned about the weight of a 72" std duty with large loads. But I am also concerned about the toughness of the light duty over time.
I am trying to get the weights of each unit from the company.