Its my understanding that only the MD-11 has a de-iced horizontal stabilizer - that is because our friends in Longbeach in their efforts to make the three-engine bird have the same economics as Boeing's big twins - did a relaxed stability, undersized horizontal stabilizer to reduce wetted-area drag in cruise. In order to re-cover the control authority - they use a nifty "vented" hinge - that acts like a split flap horizontal stablizer - to soup up the aerodynamics of this fin. The only problem is - that if the "vent" gets obstructed with ice - the control authority gained could be lost. SSSSSSSSSsssssssoooooooo, that added anti-ice to it ..Also, They got this big assed engine just up the stabilizer which provides a conveninet source of bleed air .. Would hate to have to plumb air from the wing root all the way back to for occasional de-icing ..They also have a fly-by-wire design so as to control the the relaxed stability design.