Patrick,
I dug up an old mango (about 10+yr old) and transplanted to another yard same day. It died in about 6 months, did not have much roots except for a few large roots that I had to cut off to dig a 3 ft diameter root ball. I have done similar transplant on persimmon, aprium, loquat, citrus trees planted in-ground and transferred into large pots/containers and they did survive (also all about 10 yrs old). My mango tree did not have much smaller roots so that may be the reason it didn't make it. I did trim back all the branches on the mango trees and left only minimum green branches on it after the transplanting.