Attached Link: http://www.renderosity.com/viewed.ez?galleryid=828377

I too was wondering about this, and I think there are ways to improve the quality of terrains in Vue. Procedural is certainly one way to go, but I've also tried using the resolution doubler on the terrain editor. I think by raising the resolution of your terrains, you can get more detail in them. Combine that with good textures and I think we can come close to the terragen ones. Check out the link for a really detailed terrain in vue.