They explain the balls spreading apart as they accelerate rolling down the bump. What about the balls compressing as they go back up the bump? Wouldn't the balls constantly collide and separate?
Really, it's almost like replacing the cage with a subtle bumpy bit in the race. And that seems less-crazy.
But without the grease, wouldn't it suffer the same as greaseless caged bearings? Albeit slower wear? Perhaps the wear is reduced enough that you'd be willing to replace them more often in exchange for the lower losses through friction. I dunno; I really think this just needs a (perhaps literal) ton of testing.