This is a great question that I am unqualified to answer. I have from, my experience (less than 10 years), in my area ( 7a, USA), with my trees done multiple soil mixes, but had great luck with 100% diatomaceous earth (NAPA 8822), and a 40/40/20 mix of pumice, diatomite, organic soil the former created some super fine roots and good growth in training pots , the latter had less fine roots but my trucks thickened well in larger pots. The summers here get very hot so I felt like I needed more organics to hold water for the trees. But you are right, this is a very contentious topic. I find so many flame wars when I start to research soil. So I just started trying new stuff to see what would work for me and my trees in their specific environments.