C. tetrameria #6 (there also is a #7, both results of a taste test by CRFG) is a good fruit, different from the white sapotes. Here in California it is called a yellow sapote. I have dwarfed C. tetrameria greatly by putting it on C. casimiroa edulis (white sapote) rootstock. Your future growth on the scion could be limited. I have two C. tetrameria trees (#6 & #7) grafted on white sapote rootstock and they are 15 years old and only 6 ft tall. C. tetrameria grafted on its own rootstock makes the tree 15 ft tall. C. tetrameria is not a huge tree like C. casimiroa. Fruit is large, seeds are much smaller than the white sapote. I do have Walton and Nies, but have not tasted the fruit yet.