>> Is there some kind of mesh data that does not survive an export from Modo to .lwo format and back in again for example?

Nothing as far as I know ... only shading descritpion is lost. (In fact basic texture maps in common slot like diffuse, specular, bump are preserved ... but advanced
settings that is to much different from lw don't work of course)

You can even rename a .lwo into .lxo ... it will load perfectly in modo (I'm not sure it will prove anything :))

*Edit

They are some little stuffs that are still not preserved

- Patch geometry
- UV's are allways stored back to linear

Btw I've renamed a .lxo into .lwo, but the file can't be loaded in lightwave modeler.

I almost forget :

Nice rendering Danny ! Maybe the glass material can be a little bit enhanced ? (adding some refraction ? fresnel on the reflection ? I don't know ... looks just 'transparant' for the moment)