This thread is for helicopter techno-deviants, and perhaps the very bored.
I claim, with absolutely no modesty (and even less knowledge), that it will be impossible to significantly decrease rotor-induced vibration by physically changing the pitch of the blades. Their moment of inertia about the feathering axis will prohibit oscillatory rotation at all but the lowest of frequencies.
The following is an article from this Saturday's paper, about the work of two 16-year-old students. It conjures up the idea of using electricity to modify the aerodynamic profile of the blade, without changing it's physically profile. This should allow rapid changes in its lift, many times in a single revolution.
Ions & Air Resistance