I tried exporting a complex terrain to all of the available export formats (dtm, tin, .xml, fil, and txt). When I create a new terrain from any of these exported files the triangles don't match the original terrain. I think the underlying terrain is being reprocessed, thereby losing any terrain edits that may have been done. I think this happens on any edited terrain, not just complex terrains.
This seems like a defect. Am I expecting too much?