"The history of the shapes is a bit different, as is the way the used to be used. Because of the tip on the kamagata usuba, chefs can use it for regular usuba work and mukimono (design work), and tend to do so. In kanto, chefs that do mukimono tend to use a mukimono bocho as well. Of course, at the best restaurants and with the most skilled chefs, they still tend to use the most task specific knife (but, not always).
There's a bit more history to it than just that... i'm in a rush right now, but if i can remember tonight, i will explain in more depth. It will also clear up the difference between takobiki and yanagiba."
and later, i was able to post this:
Hope this helps you guys better understand these knives."