Daz Studio Pro now has GI and a 64 bit version so it's acceptable for rendering, provided that you have the content already. Carrara doesn't have a 64-bit version at this time, so, although you could build scenes, with superior modeling capabilities to Vue, the scenes would need to be somewhat small, and you'd be faced with limited and somewhat unrealistic atmospheres. Vue can't be beat for outdoor rendering and there is nothing on earth quite as cool as generating and painting ecosystems. You can easily import models from other applications, including Poser, but you may need to tweak the materials. 

There are reasons to use multiple applications, but there is also the time factor. Right now, I have no use for Carrara and Daz Studio Pro and am focusing on Vue, Illustrator and Modo. It will likely remain like this for several months to come, until I complete my scene. 

Download my free stuff here: http://www.renderosity.com/homepage.php?page=2&userid=323368