Fantastic image in any version. Personally I feel like the later revisions lost some of the peacefulness and simple beauty of the first one, but the addition of objects definitely helps the realism of the ground. I've just finished driving from San Francisco to LA and back again and you do see a lot of open ground, with few trees, mostly just smooth grass. For my taste I think I'd prefer to see maybe a single windmill strategically placed, and then fewer trees in realistic clumps (maybe in creases in the terrain where water might collect).
I think the reason for the line in the first version was that when using 2D clouds, the shadow rendering of the terminator (where the sun is cut off by the shadow of the planet basically) is less realistic and "harder" when there is no volume to the clouds. 3D clouds handle this more realistically.
- Oshyan