Phantast, I suggest you create your own SG plants and let us know about your results. You'll soon see it's a lot more difficult that what you are saying. C3D plants are either created by e-on, with their proprietary technology, or modified species, like all the veggies made availablre by the lovely Frenchkiss. Call them variations if you want, but they are true new species, and high quality ones.

As for Xfrog plants turned to .veg, there's no way this can be done. Xfrog plants are the best around, but the poly count is a lot higher than .veg