Both versions of Vue import pz3 directly. With Vue 4 Pro and Vue 5 Esprit+Expansion modul you can modify a character or scene in Poser and after you switch to Vue it will ask to import the modifications, which is a very nice feature because there's no need to rearrange the character or scene in Vue again. Vue 4 is more solid when it comes to large scenes. Vue 5 has fantastic new lightning options (if you can handle the render time). It's hard to tell which version to take, I think it depends on your preferences.