I asked my husband (who went to Darchei for BM) about the Darchei conflict and this was his explanation:
Darchei is yeshivish. They also have a really strong secular education for the members of the community that want it, and to ensure that their kids can go out and do well if need be. The secular education counterbalances the yeshivish leanings of the school.
In Beis Medrash, without the secular studies, only the Yeshivish philosophy is left. They push hard to keep you learning.
So to sum up: the high school is yeshivish and you get top notch Jewish and secular education.