Because of the blend-shapes have overlapping, non-orthogonal effects i tried toachieve some flexible facial rig via wire deformation. System works like that:

*For better control of weights i used geometries controlled by wire tool.

*These geometries add to skinned geometry as influence objects.

*Also wire curves are skinned with joints for decreasing controller numbers and giving better falloff.

*On final stage deformed geometry used as an active blend-shape weighted 1 to final skinned geometry.