Be careful with scaling when importing an OBJ in to C4D. Generally you need to tell the C4D importer, or Riptide if you use that, to scale the object up by 1000 or 100 times (depending on what did the export). If you don't you will end up with (to C4D) a very tiny object that will have all kinds of weirdness including an inability to render properly. To test this, create a standard 200 unit cube in C4D. Then import your OBJ into the same scene. Adjust the scale so your model comes in at about the same size as the cube.

Hello,

Not application specific but MG's MergeOBJ utility is a great way to save out different levels of detail and then merge those multiple OBJs into one. Some components just don't require the level of detail that others do, hopefully this functionality will make it into MoI itself.