If you save as vob, it will look different than using the Poser shaders, because if you use the Poser shaders, Poser will do the rendering, not Vue. This option requires double amount of ram, so you need a strong system.
If you don't use the Poser shaders, you will need to fiddle with materials a bit, for example Poser uses the colour black for highlights, very specific to Poser ( it's actually the only program I know that uses black for highlights), so you'll need to modify not only the colour, but the amount and shininess as well. Some materials import reflective, when they aren't in Poser, so you'll need to look into this as well. If there are specific shaders in the Poser materials, they may not import correctly in Vue, if at all. Most of the new figures use special functions to create realistic human skin, and they may not import well in Vue, or you'll need to recreate the effect in Vue ( bump, specular & displacement maps for example), which means you'll need a good knowledge of the advanced material editor and the function editor.
Any other 3d format will be the same, only the texture maps will import (in Vue or any other app for that matter).
Now when saved as vob, you can't use the Poser shaders, you'll need to convert all material channels that did not import, but it's a fact that vob will use a lot less memory.