We have been studying the topic quite intensively lately. My understanding is that it boils down to what you want, what you are willing to do, and the tree species.
I learn that pruning is not slowing down the tree growth, on the contrary invigorates it. Pruning results in the energy reserve of the tree to be redirected on the remaining buds promoting their growth. So the more you fight with the tree the more it will fight back until it will exhaust its resources.
By reducing the canopy we reduce the amount of leaves, and thus amount of sugar the tree will produce, and thus reducing the sugar available to the truffle. Is this a problem?
We have planted English White Oaks which have a fast growing habit, there is not much we can do about that, so what we will try to do is to redirect that growth in a way that is not closing the canopy. We will NOT top the trees but will reduce them striving in maintaining their good structure with a single leader branch. We will prune the tree following the guidelines as explained in this Master Guardner Class video. Only the future will tell. We will make sure to keep you posted with our results.