Sphere itself will never work with world geometry as there is no way to actually render world geometry in a dll (well i suppose there may be a way but i dont know about it)..and the fact is, world geometry has many problems with tangent generation that make it unuseable...plus it is very slow, and limited to convex shapes.

However, after the Octree update is available, then maybe the mesh system will be differnt , so Sphere should be able to use the world models you can import.