After playing around with the instances I decided to revisit my for ever unfinished "Green houses" scene.
Well I wouldn't say it was simple, a very huge work to export all the scatter files, to import them and organise all that stuff in a messy huge node graph but the result is quite satisfying. I also had to work a lot to get everything fitting in the 64 color textures and the 32 monochrome avoiding the repetition impression.
The main annoyance is definitely the loading time, about 12 minutes.
Assuming the scene with instances has about 15 million poly the rendering time is quite acceptable, but I mainly used the directlighting mode.
To be clear, all the trees are polys !
So enough blabla, here are the results.
Not only it's very realistic, but there's a great 'atmosphere' in your images.