@LO23M8B
I use to believe this as well, and all that has been said about it, made sence with the alu dissipating heat and all.
Go become a member of Motor Trend On Demand if you are not already. it like 3 buck a month!
Then watch this video from Engine Masters: They take and identical head that was available in alu and iron.
It was a vary well sorted out test. Worth the 3 buck membership and all the great other programs(I'm sounding like a salesman:BangHead::D) https://www.motortrendondemand.com/detail/iron-vs-aluminum-heads-a-study-of-heat/0_623whon4/