I have used Truespace 5 and Silo, I had the same problem with both. I love Silo, but after being able to create with ease with this program. A Porblem that has happened with both programs is. 

Example, With Silo. I made a tables and drawers. What Looks great in the Silo window, when imported into Poser, The nice square lines from Beveling within Silo, come out with slightly rounded corners where they are square in the Silo Window. I had the same thing happen with TrueSpace also.  The model was exported in 3Ds.

If someone could give me a clue. I am using a Silo Demo, and hopping I can fine the answer. I can do some amazing stuff faster in Silo than any program I have use. A complete WW2 tank and an Airplane that I want to use in a movie I am animating. And I'm have little experience in 3D modeling. I guess my queston anwers that.