Just to back up what I've said. Don't go to crazy with these things and try to make settings so that you don't get a lot of small rough details all over the place otherwise it won't look smooth and realistic. The terrain provides detail and further overlying displacements can provide detail. Some displacements can have low detail and be very smooth, just providing a general shape, otherwise you'll get clashes of displacement detail everywhere.
For example in the tests you guy's have posted, the terrain is already rough. Make the displacements have low detail. High smallest scale, low colour roughness etc. You'll find all this out by tweaking. My original examples are smooth but your terrains will provide roughness. It goes further though because really what you want is various layers of subtle things going on. A reasonably detailed terrain, other displacements to provide shape and then more surfaces over the top to provide the real detail. At least that's the way I work. It's not the way everyone does things but it's what TG2 can provide over TG 0.9.