moving trees and bushes

I have a question for Aranya:
We have a dry summer climate, so many small plants will die without water. I aim for a food forest, but some of my plants are not full size yet to produce shade and make use of full sun. I usually aim for semi-dwarf fruit trees 10-15 feet high. I have often moved trees around when I realized they were going to be too big. I find that they grow more quickly in full sun, but I have to water them more. I know Paul Wheaton is very pro growing trees from seeds, but then you don't get the variety you want, you get a random flavor from nature. You also don't get to find out what they taste like until 8-10 years later. Trees that are moved lose their tap root, if that species has a tap root (many don't) but larger trees can withstand a dry summer better than baby seedlings.

Where do you stand on grafting/moving trees to fill in sunny areas as they grow up, if they can't shade anything as tiny seedlings?
Thanks
John S
PDX OR