I think a Windhammer is better. Even though it deals about 1/4 less damage than a perfect, double-upped Bonesnap, it has a whopping 60% IAS and more %CB. They cost just a few pgems, i.e. far less than just the upgrading runes for bonesnap.
It's a nice leveling weapon for an IK barb, although I prefer Steeldriver for that (to be upgraded to exceptional at L34), because of -req and IAS... CB isn't really needed before hell mode.