Agreed. And, while I have no evidence of this, my intuition is that the extra GPRs you get in 64-bit more than makes up for any minuscule system-wide performanc

Agreed. And, while I have no evidence of this, my intuition is that the extra GPRs you get in 64-bit more than makes up for any minuscule system-wide performance hit 64-bit long-mode paging imposes.