Well it's a bit a pitty to remove or lost the vertex map in modo, this is a really important data to have clean render without surface smoothing glitches.
There are many solution to export your model, using .lwo or .obj. ... but there are some rules to keep the vertex map clean.

- Do not copy/merge object in a new layer inside modo, or you will lost the vertex normal info
- Do not modify the geometry inside modo for the same reason.
- I was able to do some mirror, seems to keep the normal info ok, if the mirror result is in the same layer.

When exporting in .lwo, you can use ngone without problems (at least I didn't had any problems so far), however, if the object is complex, you can have thousands of little objects (layers) inside modo, and it's not very handy to manage. And as you can't merge them inside a new layer without loosing the vertex info, it might quickly be a problem.
(Every little object has his own vertex map info)

In .obj, you can use the MergeOBJ editor tool that Michael creates, it will merge every little piece in on single object/surface ... and that's really cool.
However, .obj in ngone comes with some troubles (flipped surfaces), but a little Polygon > Align in Modo will solve the problem

Using Quad/Tris is a good solution to avoid any flipped poly problems, but the mesh is a little bit messy and no easy to uv unwarp for example (there are a lot of micro triangles that are not handy to select).

I'm quite please so far by exporting in .obj + MergeOBJ + Polygon > Align in modo ... but you still have to check the geometry closely to be 100% sure that every normals are in the right direction.