@spaugh
if the tree remains vigorous for you on its own root, it doesnt mean that if you graft it onto a random vigorous rootstock it will keep its vigour.. does it?
or does the scion transfers that ability as well?
What if you graft it onto a less vigorous rootstock, can it improve it?
or once you graft it, that means the rootstock "takes the lead" from that point onwards?