Other downside is that magnetic force falls off very quickly with distance, so in effect they're a non linear spring, in this case they'll have less force when engaged, than when the teeth are riding over each other.
the two magnets have the least distance between them when the pawls are fully engaged, im guessing that'd make the attraction strongest in that state. but to prevent skipping, the magnetic force is most needed when the tips of the pawls are just touching (they'll never fully disengage because the magnets pull them together). So the magnets will have to be pretty strong, magnetically speaking
If it were worth doing to reduce rolling resistance, shimano or some other major manufacturer would have done it.
i'd give them the benefit of doubt, i like seeing innovation nevertheless. it's fine when a thousand new ideas fails, since we just need one to hit it right and it changes the industry. This hub, for instance, has one single moving part only. best wank material for engineers all round amirite?
they claim they use "neomidium magnets that pretty much last forever", so i looked it up:
1. strongest permanent magnet commercially purchasable - "Neodymium magnets larger than a few cubic centimeters are strong enough to cause injuries to body parts pinched between two magnets, or a magnet and a ferrous metal surface, even causing broken bones" from wiki
2. very vulnerable to corrosion so it needs protective coatings - should be fine being inside a hub
3. very brittle - "Magnets that get too near each other can strike each other with enough force to chip and shatter the brittle magnets themselves". even if they're well protected from killing themselves via engagement, it's hard to imagine how they can withstand sudden shocks like an icepick or even slamming the end of the peg into the ground