Chromoly outboard Spindles? are they worth it?

I know there are some axle or spindle that uses chromoly like the 19mm axle for the bmxs. But (for me) I never heard of a chromoly on a Fixed gear crank. But i know 2 outboard crank that are using these chromoly spindles. They are the Rinpoch RC2130 and Rinpoch Hex. (not sure if you heard this...