I readily acknowledge that the Haredi system is better at producing Jewishily knowledgable and fervent kids than the Modern Orthodox schools. Clearly, if the question was keeping kids religious tomorrow, Haredim would win easily. But the lesson of antifragility is that you have to prepare for the extreme. Breaking Haredi kids should be relatively easy. There is no need to argue with them. Take away their tzitzit and yarmulkas; clip their peyos and let them see themselves in the mirror. No need to force them to eat non-kosher, just let them feed themselves from a dining room not designed for kosher eating and make their own compromises. The fact that these compromises may be quite defensible will not change the fact that they are compromises. Once you create a break with their past selves, the rest should follow easily.
Remember that Haredi kids have not been trained to imagine themselves living outside a Haredi community. On the contrary, they have been conditioned to make that imaginative leap impossible. Thus, the moment you take them away from their community, they will likely see themselves as different people. This is not the case with Modern Orthodox kids, who have identities distinct from their Judaism. This might make them less fervent and more likely to abandon the faith on a day to day basis. It also might allow them a stronger sense of continuity even under difficult circumstances. As long as mental continuity exists then Jewish identity stands a fighting chance.