jm, thanks for posting my review

I think graphites are great practice chucks, as they are extremely sturdy and well-balanced.
The cracks would probably be either chipped edges or cracks in the paint; you would have quite a hard time cracking the actual body of the chuck.
I liked to learn aerials with them, as they are weighted well for aerials, and if I dropped them, I knew they wouldn't get dented. When I lived in the states and could still use real chucks, I lived in an apartment with a tile floor, and dropped them constantly. They kept on going like the energizer bunny.
That said, wooden chucks can be amazing if you find the right pair. I say, experiment and see what suits you best. Chucks aren't all that expensive, compared to other hobbies.