I have lots of experience running aluminum main caps on stock BB Mopars. I like them if you want to run steel rods. If you are willing to run aluminum rods, then ductile or steel main caps are the way I would go.

I would still inspect aluminum caps for cracks at every rebuild/freshen-up. A very close look can catch a crack before it goes all the way through. And I even found cast iron caps cracked in half at an inspection before the block let go. Set an inspection interval (maybe 2 years or 500 passes?)