aluminium head questions

Now I'm not so sure... I'm finding a lot of posts like this:

http://www.cuda-challenger.com/cc/index.php?topic=52902.0

I know that's just a few folks opinions but the exposed gasket and dropping valve issues seem to be repeated on several forums.

So, back to the MP heads. Everyone claims the "452" head (5153524) is the same thing as the Edelbrock RPM (in fact made by Edelbrock w/ a Mopar logo) but w/ straight plugs.

What about the MP 4876311? I can't seem to find any feedback about it. I would think it's a better choice since it has a smaller, closed chamber. Do people not prefer the factory 906's over the 452's for the combustion chamber? Why is so much made of the "452" Edelbrock copy head but so little mentioned about the "906" 4876311 head?