Yup, I agree. They do fruit a lot. I hope to taste the fruits this season on my grafts. Since I have my trees outside, I just let them grow and see how tall they will grow before I cut them way back later in summer. My Black Pakistan tree that I let 3 tall branches grow without topping got to about 18 ft in 2 years before I cut it back to 10 ft.
I heard from some members that the World's Best is the same variety as Thai Dwarf but I'm not sure if that's true. My grafted World's Best is a very slow growing graft.