It's not true that we only have 3 "layers" at our disposal ... Like ello pointed out some time ago, you should make a skin texture which has a lot of details already and the main colors/textures. (Since 3dgs chucks the terrain, this base texture's size may be quite large actually ..) Then through the shader you add 3 or more detail textures through multitexturing... (Infact 3dgs support about double that amount anyways.) It's a matter of how you're using the options you've got, not limiting yourself to blind stare on some pre-made features like in BV. Yes, it's nice and it's very fast when making terrains, but still ...

Cheers