Height of grafts on nursery rootstock: mine end up average of waist-high.
Seems not to be a problem even on vigorous rootstock varieties. Unless of
course the graft rejects, and then the rootstock usually wakes up.
The only problem I've found is, what if I decide I want the topwork to grow
its own roots? Then I have to dig a trench in order to get all the
rootstock below ground.