While I'm not against your proposal per se, the way you call the low-achieving kids "dullards who may never catch up" is a red flag that you don't really understand what puts these kids there in the first place.

This grouping may benefit the geniuses, but the system isn't really holding back the geniuses. They succeed despite the system, not because of it, whereas the system is failing those lagging behind. Implementing this plan on an American school system without addressing the laggards would just be shuffling around the furniture.