Have y'all gotten financial aid responses yet: workstudy eligibility, etc? From the website, it seems that there are a lot of opportunities to work on campus and in the Pittsburgh community.
I am under the impression that the living expense estimates are inflated. Keep in mind that they factor in insurance, an expensive laptop, travel, and probably a high estimation of housing costs and meal costs. I think that they want to make sure you can spend/take out as much money to live comfortably while you study. You could probably cut costs here and there.
I would say go for the money holding everything else constant. I'm not sure, but it seems as if the schools have really different curricula, so you might also want to think about your exact goals and which school will prepare for those goals best. Personally, I love Heinz' course offerings. It's exactly the type of education that I want, but to each his own.