There's a pretty good discussion over at Swordforum.com regarding these synthetic bokken, and the consensus is that they are too light for normal use.
My opinion? Not worth it. If you want something that has excellent resistance to impact and doesn't break your bankroll, get one made of high quality hickory wood.
Thanks for the replies. I read in a product review that the CS Bokken vibrates a lot when stirking. Not what I'm looking for. So I pick up a traditional wooden one.