Personally, I do not consider any AP courses a substitute for college level classes at any college worthy of being called a tertiary level institution.
This is dogmatic. I earned a 5 on the AP Calculus BC exam. When I went to Harvard, I glanced a few times at the homework and exam questions being given to Harvard's "regular" calculus class (the one taken by biology, economics and other non-math majors). The questions were on material I had seen and were not above the level of my high school calculus class. In fact, the calculus textbooks authored by Harvard instructor Deborah Hughes-Hallett have often been criticized for their lack of rigor. I started with multivariable calculus and was not hampered by not having taken single-variable calculus at college.
I doubt that Harvard's "regular" calculus class is much more difficult than that of other colleges. Its Math 55 course probably has counterparts at only a few selective schools. Harvard et al. are so expensive that it makes sense to take courses at them which are not offered at other places (including high schools).
