64 Bit Extensions on Merom/Conroe, will likely be developed with at least their lifetime memory capacity requirements in mind, and we will have to see if it is inferior to AMD's.
On die memory controller, is not the be all end all of things, Intel still has reasons for leaving the memory controller off the processor as Intel likes to play with different memory types, as well as Intel has a chipset business.
I am not discussing whether or not Intel developed, 64Bit Extensions, but it is a technology used by the Pentium 4 nonetheless, and hence a technology of the Pentium 4. The experience of implementing 64Bit into Pentium 4 is useful. And if your trying to utilize how NetBurst technology benefits from 64Bit Extensions as a judge of how good Intel 64Bit Extensions are I don't feel the comparison is valid, as Pentium 4 was never designed with 64 Extension use in mind, and more as a tacked on thing in case it was needed to be used as a marketing tool, or it could be the way AMD design 64 Extensions isn't optimal for NetBurst.