Maybe the problem is in C4D.

The MoI -> Modo workflow works a dream, particularly with materials. If I re-import a model in to C4D, perhaps because I have made some change in MoI, C4D messes up the materials I have already spent some time creating.

In contrast, because of Modo's layered approach, Modo imports the new LWO file and adds a new material group. All I have to do is delete the new material group and the masks revert to where I was before the re-import. Dead easy, and something Maxon need to address. Modo's masks directly replicate the styles set in MoI.

I also have Rhino, and one of the big selling points of MoI is it's ability the mesh the Nurbs in a fast, controllable way, with n-gon support and welded vertices. Rhino's meshing is, and always was, horrible. I now use Rhino just for things MoI fails at, like some complex surface creations or hard to do fillets. I still import back to MoI when I've done the Rhino bit.

Why would you want import anything other than meshes anyway? I have the lights and materials set up in Modo, and re-importing the MoI LWO file doesn't disturb them.

I can't really understand the request for MoI to save it's meshes in the 3DM file. It's only 2 clicks to save it out in various formats that can be read by most polygon modellers.

Modo doesn't need this plugin so neither should C4D. I wouldn't like to see the file size of MoI's 3DM filles increase because of a limitation in C4D.