pH is only one part. Wothout sunlight photosynthesis will happen.
Akadama is a hardened clay SOIL. It is not used in hydroponics, and would not work if it was.
If it is good enough for the Japanese then it is good enough for me. It has an average pH of 7. My trees are all or will all be in 100% Akadama. The ones that are not are the ones which I have bought and could not repot as it was the wrong time. They will be done at the earliest opertunity.
As I said before, it is my choice and will remain so. The majority of growers I know use Akadama, either only or with some other ingredients, which they consider is better for them.