Walli,
Great to hear from you.
I use both SpeedTree and Maya 2011 to develop the trees. All textures are of my own creation.
A lot of the work is Maya related due to the nature of the SpeedTree software. It is designed for Game Dev for programs like Unreal game engine and others. Maya allows me to add edge loops and build in finer detail using the polygon modeling tools. When I have completed the tree it's difficult to tell where the object was created. SpeedTree is basically used to create the base mesh. The majority of development is done in Maya.