I really like what I see so far.
I don't have the best test scene but I really like the "patch" entities as just a few of these sprinkled around add a nice sense of life to even a simple natural scene. I like being able to switch between the wind variants, but the default low wind variant is rather subtle and the strong is quite, well, strong. Animations are probably a pain but I could see if there was an option in the middle using it.
Seems like the meshes don't have the skin variants defined? You can find a bunch in the general skin browser but nothing limited to the model itself.
The larger patches look great, especially at a distance, but they don't hold up as well close up. Part of that is a given with billboard alpha, but iirc in the original test map the large tufts have a sort of dense ground cover that pops in at a very low distance, but this kind of fleshes out the tufts when you're standing right in the middle of them, which I imagine as a sneaky thief you're likely to be.
I don't really see an issue with performance, but I am not pushing as many of these entities as something like the original scene might.
Really cool work and I think these will be an awesome addition!