tritree/scenetree KDtree balancing ?

[OnoSendai]

I think it's more complicated than just taking the sqrt.
There are other issues that need to be considered as well, such as instancing, and non-mesh primitives.
For example, lets say you want a forest with 10000 trees.
Then you would want a kd-tree for the tree model, and a global kdtree to speed up the tracing of rays thru the forest. But in this case you only have to have the tree kd-tree once in memory, so it makes sense to split it up in this way.