Meanwhile i have tested it with a simple 3 part object made in Wings3d,no problems
at all.Tg2 converts the geometry from quads to triangles,but the UV mapping is not
affected in any
way.You just have to separate the parts(after the tgo to obj conversion)
again and set up the materials anew for export (that's what gives you the parts shaders in
TG2).And then in TG2 you'd have to reassign the texture images(bump,displ,spec) of course,
or do what ever is required for use in other apps.
As for problems like those shown above my guess would be that it depends on the software
the original obj file was generated with as there seem to be many different approaches for
saving/generating obj files.And some may cause
problems.Like the problems you use Poseray
for.