For those of you wondering what I meant about inboard and outboard blades, take a close look at this photo and you'll see what I mean. Since most lift occurs on the outer portion of the blades, the B2B was designed with flapping and lead/lag hinges that bisect the larger inboard portion from the smaller outboard portion. In addition to the short mast, this seems to be the reason why vibrations are absorbed so much.
***edited to add photos and animation***