Thanks! I do highly recommend all of the Onyx products for making 3d landscaping for SketchUp and for V-Ray proxies. You decide what the tree looks like and how many polys. Endless creations from one purchase. When you buy pre made trees on the web you are confined by their 10-20 trees and cannot be as creative. Onyx is also great at reducing and optimizing models so you can make SketchUp plants and are fairly low polygon.
Another tip - Being able to use geometric leaves cuts your render times down considerably. I would only recommend alpha transparency on leaves that are in the fore and middle ground of your project. If you are rendering a forest, I would definitely go with the geo leaves.