In terms of a general statement, its a bit misleading to state that sintered metal gears retain the improved strength of traditional metal gears. They are a lot stronger than plastic gears, but in the majority of cases (particularly in hand power tools), they do not have the strength of traditional machined gears.

Metal injection molding is the hot technology in consumer durables.

https://en.wikipedia.org/wiki/Metal_injection_molding

As I understand it, the legendary Sturmey Archer bicycle gear hub used sintered internal components, as early as a century ago. Those hubs have extreme longevity. Of course a bike is not a super high power load, but still it's impressive.