I was wondering the same thing, in fact I made a thread about it. Nobody really has any insight either way so I figured somebody has to figure this out. I guess it's going to be me?

http://www.americanfastener.com/astm-sae-and-iso-grade-markings-for-steel-fasteners/

The aluminum threads will pull out long before the stud breaks if you think about it. The studs have a flat for a wrench in the middle so they are not even full radius in the middle. Oh well that's what we are using.