I had major root problems with an old old established flowering crab tree. The roots are just as bad as the silver maple roots I think. My original hosta bed was under the crab and over the years I moved almost every hosta that was under it. The roots would grow right into the root mass under the crown and stay there. Sagae, Collector's Banner, and Tokudama Flavocircinalis were the only hostas that didn't seem to be effected much by the roots, but I'm sure they'd have been much larger by now if they'd been somewhere else.I had a heckuva time getting those roots out of there. Even ones I moved quickly out of the way of a new water line a couple of years ago. When I redug them to pot last year, I found the crab apple roots still alive and well in the root mass. I thought that was pretty bizarre.
And I am one of the crazy ones. When I moved my garden to its new location for the tour this year, I planted everything in pots. Several reasons: I didn't want to change the look of the 'land' where I was moving them too; the soil here is not good in several places; hauling in more soil/compost would have been very expensive; lots of tree roots here too, but not the same kind; and if/when the hostas move back to Corning, they'll have to deal with tree roots again. So I got the copper coated cloth, cut it into small squares and duct-taped them to all of the pots I planted in. I would not advise it unless you have a ****load of time to kill well in advance of digging and potting your hostas. It took me at least an hour to do a dozen pots no matter the size of the pot. And I did a lot of big ones and a lot of small ones. Set back the speed that I was able to move the garden. But I didn't have the majority of the pots until late July. And I was doing it for about 700 hostas. As I said, I'm one of the crazy ones.