First of all, I think that the capability of Vue of creating more than one terrain is underused. I think that this stems from the fact the the most important application of terrain generators is for game development and inside game engine terrains are subdivided into sections and not creatively assembled the way we can with, e.g., Vue.

A terrain creation program like GeoControl has to do everthing in one shot while with several Vue terrains we can have different resolutions for near and far terrains, we can mix standard and procedural ones and we can mix terrain features so, as a first idea, it is advisable to split the overall terrain into components. E.g. nothing prevents us to mix a smoothly rolling plain with  alpine peaks in the background. Creating such a terrain with any program is not easy (and quite likely amounts to create two different terrains and mix them appropriately).

Also, something I learned from GeekAtPlay tutorials: the different terrains can not only be translated and scaled appropriately. but can also be rotated and sheared. No existing terrain generation program can create overhangs: with Vue nothing prevents to to create a "mountain", scale and rotate it into a thin peak and then shear it to  a side, covering another part of the terrain.

As I showed in past threads, Vue terrain are not as sharp as GeoControl or WorldMachine show, especially the standard terrains. This is somewhat a non problem because, as soon as you add a texture to the terrain, 1-2 pixels wide details are completely drawn by texturing. Terragen2 terrains look spectacular because they are the result of a first fractal detailing at terrain level (always present UNLESS you deliberately turn it off from terrain nodes), plus materials which provide true displacement to the surface; the Vue equivalent is to take a terrain, use it as a base for a procedural terrain, and then texture it with a displacement material, adding as last component days of experimentation because TG2 renders are never the result of 20 minutes doodles!

The border artifacts shown above are not actually artifacts... do you notice that for every right peak there is a corresponding real peak on the left (and if the data were different, there would be visible upper peaks for each lower one)? well it is a bug (which I read manifests also on image based materials). The work around is very simple: in the Projected Texture map node there is a pair of fields tagged Scale: just a set them to 1.01 (i.e. a bit more than 1) to enlarge the terrain slightly and push the artfacts outside the show area.

W.r.t. interpolation I prefer bicubic because, tought  it is smoother then the other alternatives, does not introduce artifacts (Vue should introduce Lanczos interpolation).

The moire-like artifacts are almost surely due to an 8 bit heightfield bitmap. Check carefully the bit depth of the bitmap, best with a completely indipendent application (bugs happens...). TGA export is usable in Vue only for standard terrains while .TIFF can be used both for standard and for procedurals. B.T.W., if you are looking at terrain details, the 256 level stepping can be used deliberately as a kind of level curves.

Bye!!!

P.S.: before even trying displacement materials on terrains, save your work. I have just recently been able to use them, with 64 bit Vue on a 8GB vista box; before, in the 32 bit era on 1GB computer it was a sure recipy for a crash.

GIMP 2.7.4, Inkscape 0.48, Genetica 3.6 Basic, FilterForge 3 Professional, Blender 2.61, SketchUp 8, PoserPro 2012, Vue 10 Infinite, World Machine 2.3, GeoControl 2