Quick workaround is to mapimport the SDF file back into C3D and scale it, then mapexport to SHP.
I'm surprised this isn't an issue for people. How do you exchange accurate information for GIS, which is what most advanced H&H programs run of off? How do you display your pipe network for KMZ files? Quite simply: How can you provide your Civil 3D design data to be spatially coordinated with most mapping platforms - Including Infraworks?
