[apalrd]

I would guess that the gear would still fail before the stainless dog (or possibly at this point the 7075 hex shaft would become rounder), but the failure load would go up quite a bit relative to the 7075 dog, but that is just a guess. YMMV.

The dog is a tiny, high-load piece with many stress risers. It is subject to significantly more overall stress than either gear mating, as it sees loads when in both high and low (as opposed to only one of the two) in addition to shock loads during shifting (again, ~2x that of either high or low). It's small enough that, even in stainless, it only weighs 0.044 pounds (According to AM website).

I have never run aluminum shifting gears in a drive gearbox, so I can't comment on durability with good evidence. I have run aluminum gears elsewhere (in FIRST) and seen failures of many aluminum parts (not in FIRST).