I believe I get a much stronger tree when direct seeded in their permanent location. Tap root trees simple do better if their root has been allowed to grow fully instead of in a pot. It takes a little protection to make it happen but I think it's worth it. Of course I do pot starts too as I enjoy growing trees, just don't think it's best.
I started out trying to transplant several of the bur oak saplings that the squirrels had so kindly planted in our yard in the city! You are correct - it is nearly impossible to extract the long tap root fully intact.
I then tried our giant bur oak acorns in oversized pots. They did very well even under my cheap grow lights, but tended to have a long tap root that was wrapping around the bottom of the pot. When I used a fluffy potting mix, it WAS possible to extract the saplings with their tap roots intact and gently straighten the tap root into the planting hole.
That was fun and productive, but then I contemplated the growth rate of bur oak trees in Kansas. My great grandchildren will think those trees are awesome.
I have now switched to hybrid oak varieties that grow much faster and hit acorn production maturity much sooner!
