Hi Everybody,
Like the render Tom. Some of the best work I've seen with Podium. I also struggled with the trees/grass and plants problem and SU, and after a long period of trail and error and a lot of bugsplats and a SU that freezes I......... decided that SU is just not suitable for this type of things. The way to go is a workflow with another main compositing 3D software pack like Blender, Cinema4D or 3DSMax. I do my modeling in SU as far as I can. Then I export my model and import into blender for example. Grass, trees and plants are easy to import into model now. You can use plugins to spread grass or use hair particle system to create grass. Blender and other programs can handle Xfrog, Onyx strees for example and when using instancing the size of models won't be a problem. The only thing that takes time is finding the right mix of apps in your workflow that best suite you and the type of work you do.
PS: I forgot to mention Vue. Vue is very capable for creating nature elements like trees, grass shrubs and plants.
Greetz Twan