You hear this a lot, but I've never seen it substantiated anyplace. I do recall one magazine tested some World products heads in iron and aluminum and made nearly identical power with both. Also, there is more to making power than flow numbers.
I've never seen it in person but have read a few articles that stated it. I agree flow #'s aren't a tell all. Chamber design and port volumes also contribute allot. I'm sure there's other factors too.
It should be noted that there is almost no markup available in Edelbrock heads (with end of year price increase, typical wholesale price is $1325/pair for the Eddie Magnums), whereas there is profit margin in these iron heads, so a lot of vendors are going to push them.
You can buy those heads on Ebay (with springs) for less money if you do a search for Monster Magnum heads, and you can probably get them with the LA intake pattern for the same price.
You can't buy the Iron Ram heads with 2.02 valves on E-bay or anywhere else I've seen other than Hughes. That's the ones I'm talking about. Not the stock replacement EQ heads. These also have a performance valve job and stainless valves.
If I were going to spend the same or similar amount of money either way, I'd get the aluminum heads. 50 lbs off the front of the car is hard to ignore, especially if you race at all. And if you're talking about porting, I'd way rather port aluminum than iron.
50 lbs does help some. Especially at the front of the car. The old standard rule of thumb was .1 sec for every 100 lbs. that would only make it .05 sec faster according to that but due to the weight dist being better it may be .1 sec. It helps for sure but it's not a tremendous gain. I'm sure it would help handling some also. I agree porting aluminum is much faster but you have to be that much more careful also not to go too deep. I have shaky hands so I have to leave aluminum stuff to a buddy.
The Edelbrock Magnum heads should not be ignored as an option.
Steve