Another useful piece of knowledge lost in some of these discussions is that of ductile iron: http://en.wikipedia.org/wiki/Ductile_iron

As far as I recall, both Magnum and Super Bell use ductile iron for their axles. Both have been in business for decades, sold many thousands of axles, and have a published failure rate that is VERY low. That's not to say we consumers shouldn't be ever vigilant, but it also says that their real world performance history shouldn't be ignored either.