Goido,
Forgive me, I actually intended to answer your question yesterday. The Volumetric clouds are an optimization of the tools that Bryce has always possessed. The trees are more or less the same. The branches are still too angular for my tastes, but at least the leaves are decent. Carrara trees are really the most effective around, so I am more or less betting on instancing and Carrara trees for a more realistic result. But Bryce trees if you happen to like them as many do, can be exported. But I find the feature is not completely accurate, it still presents a mesh very much like your original tree. I think this is an issue that will be ironed out eventually.