I found the anecdote I referred (not sure how long ago this was):

"We were both gifted children, who had teacher parents and went to school in a very small district. The resources for us were limited, but we did all that they offered us.
I could have gone to UCONN and started as a 2nd semester sophomore since I took so many classes through the UCONN co-op program (what they offered us instead of AP). But, I got into an Ivy league college, so I went there. You know what? I was a math major and a Spanish minor. In Spanish, I was about average for kids who went there. For math, I was LIGHT YEARS behind my peer majors. I had to take 4 pre-reqs before I could start my major. Why? Because in my district, the highest math I could take as a senior in high school was calculus 1 - UCONN's version. My college threw that in the trash (not challenging enough) and made me re-take Calc 1, plus Calc 2, 3 and Diff Eq before they let me start my major. I did it by doubling up, and was summa cum laude in my major when all was said and done, but I had to bust hump to do it - and it was difficult.
My sister went to another Ivy league college and wound up in a similar boat, as a biochem major. She made it, graduated high in her class, and is a surgeon now.
My point is, we were both at a significant disadvantage because there were no resources for us in our elementary/high schools as gifted kids. We took the hardest classes available to us and we were still behind. It left us with a ton of catch-up work to do when we got to college. Now, we are both ridiculous overachievers, so we did it - but not all kids are that motivated."

So my thought is who knows what school DD will end up at and how prepared she'll be taking whatever highest course offered to her at our local school. But seems like getting the grade/credit for a high school course maybe the least of her problems. I don't care much about the grade from our local high school. It's too easy for her anyway. By the time she gets to high school she should pursue something more challenging than our AP math courses.