This threads getting interesting. Just looking at the axles in question here makes the reasoning behind using them obvious. Look at a d30, a d44, pr44, and pr60 in person up close and you can see why one breaks more easily over the other. But, we have to do what fits our own budget.
And for laughs!
http://m.youtube.com/watch?v=txSN2OazY6k
And for laughs!
http://m.youtube.com/watch?v=txSN2OazY6k