Take this for exactly what it's worth (ie you have paid exactly $0.00 for this opinion

)
Both work on combustible tinder :thumbup:
So if you carry pre-prepared tinder (vasaline coated cotton balls, charcloth, fat wood, birch bark etc, etc, etc) or have locally available tinder (like fatwood, dried grass stems, Scotish Thistle seed heads, birch bark, etc, etc. etc) both will work well :thumbup:
The advantage I see with the Mischmetal rods is that they can also be used as a source of tinder by scraping off a pile of the metal first, and using this as a tinder source :thumbup: .
Worth considering if your in an area (or circumstance), where suitable locally sourced tinder isn't available
Sure it will wear down the Michmetal rod faster (by using it as a tinder source), but they really aren't that expensive to start with
Kind regards
Mick