Yeah, I think anything anyone could say would have to be from personal experience. A lot of the “positives” could be “negatives” for some people, and vice versa. I think it totally depends on the individual. 
I agree with your assessment of transfer credits & ability to take courses in other schools, though, that also has particular requirements that don’t make the most sense (I only took EA 1, which can apply to formal studies, but I already had that fulfilled. It wouldn’t work for NatSci either, like EA 3 and EA 4 do. I understand it’s a policy they’ve implemented, but it’s sort of illogical because none of the classes in the sequence REALLY does much with NatSci).
I think many of the issues I’ve enumerated are generally problems at many institutions for higher learning. And I think there are probably fewer of these issues at Northwestern because of pressure from name-recognition than other schools.
FINANCIAL AID: I have received a decent amount of financial aid and grants and have enough saved up that I won’t graduate in debt or with high-interest student loans, but I think it’s a weird category for ambiguously-defined “upper-middle class” students, who are on the edge of income distributions but don’t qualify for fin aid. I’m not sure how the fin aid office takes into account geography or standards of living, but I’ve known enough students who took out substantial private loans to come here. I think THAT is a no-no because it places a lot of pressure on finding a career with high-income potential right out of college instead of finding something that might take a few years to build up. And the gains from coming to NU would seem to diminish in this way.
However, I would STRONGLY encourage low-income students to apply if they think NU is a good fit because I think elite institutions tend to offer better packages. Many low-income students get full rides and housing taken care of. But some first generation students (not using this synonymously with low-income) have issues with campus culture and resources to help them succeed. This appears to be improving at NU
I would just encourage people to read whatever literature exists to make a good, informed decision.