I'm using the diffuse from WM, as well the normal. Instead of displacing a mesh in Max or Blender, i'm using the Mesh Output device: http://www.world-machine.com/learn.php?page=devref#PRMO
You could export a heightmap and splatmaps from World Machine, and use those on subdivided planes, with tiling diffuse textures. We have several methods here: http://wiki.polycount.com/wiki/MultiTexture http://wiki.polycount.com/wiki/Landscape
In this amazing talk in the GDC Vault: http://www.gdcvault.com/play/1277/HALO-WARS-The-Terrain-of The developers used a tileable terrain to create a good sense of depth in the maps. They called that technique terrain skirts. In Battlefield: http://www.gdcvault.com/play/1015676/Terrain-in-Battlefield-3-A They seem to use a…