If you're doing 2D and you're using the models merely as reference....  It's those little add-ons that will break you.

The problem is, if one reference is not as good as another, and I use the poorer one, I'm going to make a poorer drawing.  Like if Roxie doesn't look as good as a Genesis 2 Female with an add-on pack...or it takes me a lot longer to tweak Roxie to make her look as good...well, then, I'd be better off not using Roxie.  I'd rather spend the money for a better & less time-consuming result.