Some month ago I played with particle-based trees in Max and Unity for a more identical output result (using different vegetation for classic renders and real-time engines is not so ‘nice’).
At the end I went with another method, but it was interesting, so I decided to give a try for particle trees in Blender.
As you see, it is possible.
There is no any additional tweaking with the geometry (yet), I didn’t assigned any vertex colors (I still don’t know if Cycles support this or not), but the result is quite promising for me.
The best thing is that this kind of low-poly trees (this one is about 3000 faces) could be used in the BGE almost directly, so making an archviz render and an interactive presentation could be almost identical in vegetation quality.
I uploaded a video to Vimeo to show the trees. At the same time I decided to check NeatVideo capabilities, too (I already tested NeatImage for Cycles renders here).
Unfortunately the encoding/conversion process eliminated the difference (on the other hand it is a quite good news), but you can see it on the single frame exported from the video.