I'm still tracing dowm some weird errors (I think Cubiquity is convinced I'm making duplicates when all I'm doing is popping things into an array) but it looks like our import/export works. AND it looks like I may have made a faulty assumption in thinking we'd only be loading single regions! But fortunately my other design choices compensated. Definitely, that reduction of 256 voxel high maps is going to be important, so I understand the need for vertical offset.