I know that they are probably worlds apart, but let me throw it out there.
We've got the Blender/CS converter (the name escapes me) so I'm wondering how difficult it would be to make a blender plug-in that does a Blender/CS convert and then runs CS in the background.
How different are they?
Well, your dream is becoming reality: the CrystalBlend project was launched a few weeks ago:http://crystalspace3d.org/tikiwiki/tiki-index.php?page=CrystalBlend
For now it's still a pure CS app, integration in Blender will come later...