dlk, that's the best of ideas: download the demos and see for yourself.

3 things Carrara doesn't have compared to Vue, when it comes to landscapes: painting ecos, spectral atmospheres, and the "decay near foreign object" parameter that V5 already has, to limit your ecosystems not to grow underwater for example. I believe in Carrara the only way to achieve this is by driving the population with a bitmap you have to create from the top view. Not as fast and easy.