I appreciate the video links, I find it very interesting what Campbell is attempting to do. I do see a few discrepancies in his comments, maybe I heard him wrong, he mentions that trees are planted at about 10 ft apart. and in one part of the video says he will increase the amount of trees per half acre, later he says he might have to pull some out.
It will be interesting to see if he is able to keep plants dwarfed solely by pushing production. having so many trees so close together, with little circulation seems like an invitation for fungal problems down the line.
In regard to Dr Campbell's strategy keeping them dwarf does work--Over ten years ago I planted a 3 gal Hatcher and the combination of letting it fruit early and minimal fertilizer(+ neglect) has stunted/dwarfed the tree.
I have already had six mangos off the tree and it still is loaded as usual. generally, get one or two flushes after harvest.
I have a similar aged Doni avocado ten feet away that did suffer some die-back from letting it hold too much fruit.
I won't be needing power saws on these trees for quite a while.