Possibly quibbling, but is it feasible that the IHS could serve as a 'heat spreader' when topped with a cheap aluminum retail heatsink? I'd guess the interface between the core and copper/nickel IHS is better than what you'd get from the core through a layer of wax to a grooved, non-flat slab of Al.
Once you're using either a high end flat-copper based HSF or a good WB, the IHS works as a 'cpu condom'....protects but limits sensitivity.
