Did you check how well the 716s are balanced? Rails are usually very well matched, but it's worth looking into. At a minimum throw them on a postal scale and see how close they are weight wise. With the additional weight in the rotor maybe it needs a little more flap than with the 696s and the dampers might need some flight time with the heavier blades to get happy. I would put a handful of flights on the 716s at the higher head speed and see if things smooth out afterwards at the lower head speed.
