Patch-based objects are converted to facets (triangles). More facets means higher surface fidelity but higher memory requirements.
Worse
Better
(more triangles)
(fewer triangles)
The "import shading only" option requires that the imported file was previously saved from StudioΓäó or DesignerΓäó, using either the "export as separate faces" or "export as complete objects" options---and that the file is being imported into the original.