[new1234567]

The article mentions slippage, grinding, play, noise and vibration. These are generally undesirable in machinery. Slippage and grinding suggest significant problems with wear and durability. That would limit the lifespan of the gearbox.

It's still pretty cool and could be very useful. That doesn't mean there aren't useful applications. It just means there are design tradeoffs.

[cgearhart]

It looks like a pretty rudimentary prototype. Many of those issues are addressed with better manufacturing tolerances, different materials, and tooth profiles. I'm not sure those features are inherent limitations as much as drawbacks to the prototype implementation.