Dave,
The place where hub springs pay off is as safety bumpers near the edge of flapping limits, where the springs save the mast by creating a strong moment that repels the head (or forces the aircraft to pitch or roll away from the head.)
The teetering head on the tilt rotors use a hub spring design as a last resort, when the head begins to gimbol toward the mast.
Mart,
The Comanche used a very stiff blade root end (about 12% hinge offset) and a metal double-plate head. The blade had a stiff torque tube so that feathering could be accomplished by spar deformation without bearings. The blade had a damper on the torque tube that tied the spar to the tube, and absorbed inplane oscillations. Very snappy aircraft, you could roll from 60 degrees left bank to 60 degrees right bank and stop in 1 second, and hit 100 degrees per second roll rate while doing so!