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really low rolling resistance
90% of rolling resistance comes from the tyres. 90% of the 10% that's left comes from the bearing seals. Hybrid ceramic bearings will, it's true, make a small difference to the remaining 1% that's down to the rolling elements.
The drive system is incredibly clever, being silent and having very low backlash combined with minimal back torque. In fact, it's so clever that Shimano put it on some cheap hubs more than 20 years ago, and kept doing so for long enough that there are even CenterLock versions.
In case you didn't notice, this post contains hyperbole, but nowhere near as much as the marketing BS issued by the snake oil salesmen at Onyx.
Silent! And they engage instantly. Not THAT expensive either (probs about Chris King price I'd imagine) although they're maybe 100g heavier than a regualr hub IIRC.
Also, really low rolling resistance (I think that's the right term)