Maybe a little off topic. We have been able to create very large levels in 3DGS by creating a real time level editor which stores the ID, xyz and rotation of an object into an array which is then saved into a txt file, when the game loads the txt file is loaded and it's values is stored into an array, each frame a loop runs through the array and determines how far the xyz position is from the camera, if it is close enough the object is created if not it moves on to checking the next value in the array. Then in the objects function if it moves far enough away from the camera it is removed. This way you can have a huge array containing 100,000s of objects, but only have a few hundred created and using functions at once. The downside is that the level is made up of only models and terrain, so it lacks the huge visual improvement of lighting, unless we figured out how to bake it.

As far as I know you can only export the geometry from WED, there may be a way by importing WED into 3D World Studio then somehow exporting to another format and get it into blender somehow, but I doubt it.