! Very good! I would recommend a good CG trick: add green (yellow, brown) variations to the tree leaves. In CentiLeo it's quite easy to do:
1) make cntlRandom
shader (with randomize by object parts
checkbox). This means: any locally connected triangular object groups will get different color/ID
2) make cntlRamp
shader and setup several knots with green, yellow, brown and other colors you like
3) connect cntlRandom to the input_map
of cntlRamp (it can be done inside cntlRamp).
4) connect cntlRamp to diffuse slot of CentiLeo Material.
The other way is to do it even without Ramp, only with Random shader. But in this case in Random shader you should switch off black and white output and tune the HUE variation range (e.g. from 0 deg to 90 hue value). That way the Random shader will generate Random colors specified by you.
I know with node editor GUI it would be much easier to observe the shaders. I am workin on it now.
The speed is ok for 980. And let's hope we can improve it further.
As for Volumetrics - not soon yet, too many urgent tasks.