Well, when it comes to pure modelling, eventually your skills and demands will exceed what cararra is capable of. When it comes to modelling Hexagon can do more then Cararra (so can other modellers people suggested).
It's probably the best to stay with what's more intuitive and copfortable till you get better at modelling, and start exceeding the limits of what you're comfortable with.

As for learning materials, many book for Maya, Max, Zbrush etc contain a chapter or two on subdivision modelling. I thumb through them pretty often. Also, a numer of books on character animation tend to cover that topic.

in the meantime... I tend to like tutorials at http://www.3dtotal.com/ffa/tutorials . I always look at tuts for other applications too, aside from what I'm using, on the off chance I pick up a trick I can use for my app as well. Plus, learning something new never hurts.  :)

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