The price point of aluminum heads as well as the evolution of the metalurgy has evolved since the grumpy days.
Plus your likely to now be halfway there to the mls gasket territory that will help you with forced induction.i have seen properly cast aluminum alloy engines make 200 psi cranking compression and work perfectly (other than seeping oil) without head gaskets. The car guys are fighting to keep heat in for cold start emissions while still using alumimum eng components on todays engines.but i agree for bang for the buck aftermarket cast iron bbc offerings are where its at

I do it for the saftety factor. In my eyes, it's similar to why do folks run intercoolers or methanol injection on higher powered engines. The 800+/- hp level seems to be ok from what I've witnessed but beyond that I don't see engine builders using iron heads that often.

Heat in the combustion chamber makes power but heat soak in the head and everything bolted to it causes power loss and possible pre-ignition.

Heres a good read. In this test, between a dart aluminum, and dart iron, they found no difference

http://www.hotrod.com/how-to/engine/...er-heads-test/

Ive seen quite a few 900 plus hp iron headed blower engines come from aome pretty big name builders.

Some quotes from folks in the industry. There's plenty of debate to go around so make your own choices;

“Cast iron has been used for making cylinder heads since the early days of the internal combustion engine,” noted Jack McInnis of World Products, Louisville, Kentucky. “Its primary advantages relative to aluminum are lower cost and durability. Aluminum’s significant advantages are light weight and relative ease of repair by welding.”

“Thermal conductivity has been debated for many years,” said Kevin Feeney of RHS, Memphis, Tennessee. “Historically, an iron head was considered more durable, and able to make more power due to the fact that it would not dissipate the combustion heat as quickly. With everything else remaining equal, there exists some merit to this argument.”

"Mike Downs of Trick Flow Specialties, Tallmadge, Ohio, pointed out that the thermal conductivity of aluminum is “four or five times that of iron. This means an iron head will usually operate hotter. On the positive side, this means the fuel is pre-heated in the intake runner and easier to ignite in the cylinder. On the negative side, it means the preheated air/fuel mixture will expand, reducing the effective flow into the engine and increasing the risk of pre-ignition. A properly designed aluminum head will transfer heat more quickly to the coolant, leaving the intake runner cooler and therefore able to flow more air-fuel mixture into the cylinder. High-energy ignition systems easily compensate for the cooler intake charge and help achieve maximum fuel burn.”

“The greater thermal conductivity of aluminum is a great advantage,” agreed Chris Frank of Frankenstein Racing Heads, Joshua, Texas, “especially in power-adder applications. That ability to dissipate heat quickly allows for more aggressive tune-ups.”

“Aluminum heads dissipate heat quicker than cast iron,” echoed Torrance, California-based Edelbrock’s Smitty Smith. “This can be an advantage in elimination-style drag racing, keeping the head temperature consistent round after round.”

With aluminum, Tony Mamo of AFR (Air Flow Research), Valencia, California, concurred, “detonation is less likely in an engine on the ragged edge, as it won’t hold as much heat. But that also firms up the argument that a cast iron head on an engine without detonation issues would make more power for the very same reason!”

“You need to build more heat with aluminum to make the same power,” agreed Bill Mitchell Jr. of Bill Mitchell Products, Ronkonkoma, New York, “or compensate by coating the chambers to keep more heat in the cylinders.”

Source; http://www.performanceracing.com/mag..._aluminum.html

Hre's something I'd like to see. Test two identical 900 hp engines, one with Iron heads and one with Aluminum. Roots supercharged engines, making the same power and boost.

Make 5 mile WOT passes and see which melts down first.
1. Test 1: 93 octane
2. Test 2: 89 octane
3. Test 3: 87 octane

Another possible test:
1. Test 1: 93 ocatane 28* timing
2. Test 2: 93 Octane, 32* timing
3. Test 3: 93 octane, 34* timing
4. Test 4: 93 octane, 36* timing... 2 degree increments until one blows up.

I've seen quite a few 1500hp iron headed engines that would last as long as any aluminum headed engine.
Too much monkey see monkey do going on here. There is nothing about iron heads that will prevent them from making the same power and lasting as long - or longer- than any comparable aluminum head. A cylinder head being made of iron has nothing to do with it's reliability or ability to make power. Nothing. (I know you know that)

Thermal conductivity does not mean aluminum heads will make more power. Port and chamber design are what make power.
A running engine will reach a steady state temperature and I question whether an iron head will run "hotter" than an aluminum head.

Problem with this is the two heads would have to be identical.

Can you explain "heat soak"?