Ok, Robert and Jack, now I did my final taste test of the Supersweet and Younghan's Gold fruits.
Robert, yes you were correct, the fruits may not be as good on the Supersweet since it is the first year with fruits. But now after eating 3-5 fruits, the taste started to improve the more I waited for it to turn slightly yellow skin. Also, the last 2 fruits fell off when I touched it slightly, so it was light yellow skin and ready to fall off the tree.
I will post some final photos of both the Supersweet and Younghan's Gold later below and give my impression on their taste.
Jack, the white sapotes you gave me (malibu #1,#3, walton, Clytia, C.Tera #6,#7) are doing well. Both Malibu #1 and #3 seems to be the slowest growing for me. The other three are growing well, they are all grafted on my McDill seedling tree and the yellow sapote seedling tree (from CSUF). I already got a small fruit from Walton this year, and it tasted good. I hope to get fruits from Clytia and C. Tera #6 & #7 next year. The Clytia is a fast grower, has many flowers now. These grafts were also on my large seedling tree in my son's yard and doing even better but i had to remove that tree and it did not make the transplant in my yard this year (lost 34 varieties).