For me, I had to catch up on the materials that I didn't learn (which took a lot of my summer away). After reading Sikorsky's response, I agree that perhaps taking it for the summer may help advance you. I know some of my friends that jump to a higher math level would self-study the course that they missed (such as trig). If independent studying is okay with you, then I guess going to a more advance math level wouldn't be a bad option.
IB is: "The IB Diploma Programme is a two-year curriculum for high school students. Juniors and seniors take six courses in various subjects, providing them with credit at some colleges and universities." If I remember correctly, I think IB has more workload than AP classes, and very competitive. You can look for more details about this by Google, or ask your high school counselor.