I might be wrong, but as far as I understand it the file im- and exporters of the current unofficial builds of blender have not been adapted to bmesh functionality yet. Therefore it is for the time being only possible to create geometry with ngons in Blender itself, but not to import it properly.

EDIT: Apart from that, be warned...
Blender is not a good solution for rendering meshes created in MoI3D. Blender has the bad habit of ignoring custom vertex normals on imported meshes and replacing them with its own averaged ones. This will almost always spoil the surface shading when rendering...