One big thing to consider is that Carrara (with Transposer) will allow you to import your entire Poser scenes, but it does not recognize your Poser shaders.  This may or may not matter to you, but it does require re-learning how to do shader set ups.

Vue 6 does recognize Poser Shaders.

Also, I've heard that Carrara has trouble with Poser 7 scenes.  I have not experienced this yet, but you might want to look around in the Carrara forum.

Carrara does allow you to model, but it isn't as intuitive as Hexagon.  So, if you picked up Hexagon back when they were offering it super cheap, then you might want to skip Carrara and go with Vue.

I don't have Vue, but the more I read, the more I am sorry I went with Carrara.  Don't get me wrong, Carrara does some really great stuff, but nothing that I need that Vue doesn't seemingly do smoother and easier.