What is the purpose of having a heavier than normal receiver, such as on the Kanstul ZKT1500A? I'm guessing that the heavier receiver is to cut down on sympathetic vibrations, much like a sound sleeve is supposed to.

Does anyone have any first hand experience with a heavier than normal receiver on a standard weight horn? Did it help? Hinder? Make it more focused? Help slotting? Make it darker?