MVP is what you want. It is Turface. I use it as a component and it makes excellent filler, retains water well, has a good size to it, and is light. You can use 100% MVP with good results depending on the type of tree. I would not put nice jbp material in straight MVP (by choice) but would have no problem doing it for maples, elms and other deciduous trees.
Personally, I prefer akadama as the main component of soil mix but it does get expensive when you need large volumes and I have yet to find an economical way to get it. Hadite is my second choice and is really economical but heavy. I don't like lava but its cheap and light. I rarely use any organics and then only in small percentages.
The Turface debate will never end (too bad all the BT discussions are lost forever). Try it. If it works for your purpose, then use it. If it doesn't work for you, then use something else. It is as simple as that.