Our assigned high school has an IB programme and the middle school that dd12 attended, which feeds into it, has an IB MYP. She has elected to choice to a different high school for next year that has AP but not IB for a few reasons. A good part of it is the demographics and that the assigned hs is in a district with lower academic standards in general. She wants more challenge so she wants to attend hs in the district to the north of us and we are fortunate that we have the option of school of choice.
In regard to the original question though, I'm not sure if she would have gone with the IB programme even if she had attended the assigned school except to try to be grouped with a crowd with whom she would feel more at home. The reason I'm not sure IB is the best fit for my dd is that we've gotten the impression that it is more about quantity than quality. Her middle school had a lot of homework especially in the accelerated classes but there were also tons of kids getting straight As who weren't doing high level work. Her lit teacher was of that opinion as well and said that he felt too many kids were coasting through as top students b/c they were fast, concientious workers who turned in things on time but whose academic skills were not advanced.
We attended an info session on IB with the high school IB coordinator a few years back as well and she stated that the IB diploma programme was not a gifted program and often not a good fit for gifted kids. She saw it more as a program for kids who were hard, fast workers and willing to spend hours and hours on homework daily. My dd12 is a deep, analytical thinker, but she is not a fast worker by any stretch of the imagination. Piling more work on her is not a good fit for her. She needs more challenging work, but not more quantity. Now, of course, we're hearing from the hs she has selected that kids should expect 5 hrs of homework nightly if they are taking all three pre-AP classes offered to freshmen. I really, really hope that they are wrong b/c dd simply cannot do that much homework and I wouldn't want her to. I don't recall anything like that in my AP classes 20+ yrs ago.
A major difference I see btwn the two, though, is that you either do the entire programme for IB starting in 10th or 11th grade which is a huge time commitment, or you don't do IB. With AP, you can take one AP class or five, so it seems like you can control the quantity a little better. I have heard people saying the fewer schools are taking AP credits and I will definitely have to look into that with dd starting high school in the fall. I'll direct her toward doing more dual enrollment (college) courses while in high school if possible if that is the case. We've been told that many colleges won't give you credit for an IB diploma (i.e. that you may not come out with the one year of college done as expected). However, I haven't looked as much into the IB claims since it isn't what dd is pursuing.