Hi Warren, I'm glad that MoI is going to be useful for you!

Yes as Stefan mentions above usually with CAD modeling you end up constructing the exact shape in the CAD system and so once you convert it into polygons you just use the generated geometry directly instead of trying to smooth it any further in your poly modeling program, which would actually mutate the shape from it's already precise shape into something else...

So for getting rid of hard edges, you should Fillet those in MoI before exporting rather than trying to round them off in Modo.

It's really pretty difficult to get a totally automated sub-d friendly topology creator - the Groboto mesher is really cool and probably the closest thing to that out there right now, but I've only really seen it applied to models with somewhat simple structures, more complex models like say an engine block assembly are often made up of a mix of large surfaces and smaller detail pieces and that's when an automated mechanism that tries to generate all the same sized quads over everything is going to have a lot of trouble I think. It's hard to tell exactly how well Groboto's mesher deals with that kind of stuff because Groboto is not able to import any regular CAD file formats like IGES or STEP files.

If you do want to use MoI to generate input for use with sub-d smoothing you would use your option #2 that you described above, - export a low poly mesh and retopo it by hand in Modo. That may be useful in some particular situations but it's not the typical workflow that would usually be used, usually you would finish the model in MoI so that it's already rounded before you export it and then just use the high poly generated geometry directly without any further geometry editing in Modo.

- Michael