Because I'm completely familiar with Poser, and an utter newbie with Carrara. Just as an
example, in trueSpace, it would take me about 15 to 20 minutes to model the Siren's hull, basic
shape. In Carrara, at the moment, I still have no idea how to even begin doing the same thing.
I've had trueSpace for years though, and Carrara for less than a week. It will take time, alas, to
be as familiar with Carrara as I am with Poser, Bryce, and trueSpace. I don't know about 
Carrara, but in Poser, I turn the models I build in trueSpace into Poser figures that are
completely posable and, after MANY headaches, the same scale as the Poser Folk. I don't
know if Carrara can do that, but again, it will take time to find out. It's one of the reason's I
hate learning new 3d apps, and why I stuck it out for so long with trueSpace. :)

Eric