I do both with no ill effects.
Root Pruning: I've root pruned trees as young as seven months old. When I was growing in containers, I would completely bare-root a tree when going to a larger container. It is okay if you pot up without bare-rooting in the short-term, but eventually it will need to be done. For the past few years, I have been putting my rooted cuttings into the ground. I have an area set aside for propagating trees. When they are dormant at the end of the year, they trees get moved (roots are cut) to a more permanent location.
If one thinks about it, at one point, the tree had no roots... when it was a cutting. It used stored energy to push out new roots. The same thing is true with a dormant tree. The difference is the tree already has converted the tissue below the root flare into a root zone so it is ready to root back out.
Leaf Pruning: I do not do this as a normal practice, but I did remove the leaves that block water from getting into a the containers. Again, this is not so necessary now that I am growing in the ground, but I still will do this on the more bushy trees with low growing leaves.
~james