My STEM kid did not even consider IB. He needed far more math and CS than was available, and went to a specialized STEM program. S1 would have been miserable trying to get through five years of foreign language. STEM program worked well for him. Got the depth he needed, then went to a school with Core specifically so he could get a liberal arts education as well.
S2, a history guy, got into the STEM, IB, and humanities competitive admit programs. He took AP and IB exams to ensure he’d get credit for the coursework he did, but did not study for each separately. The IB teachers tended to cover the AP objectives in the IB course, so he didn’t have to do extra exam prep. (Not that he did. By May he was too fried to care, for the most part.)
He had great HS preparation, but he got to college severely burned out and never really recovered from that. He has ADD and NVLD issues which the HS would never accommodate, so we had a lot of scaffolding and structure at home for him to get his work done. He got to college and managing his life plus classes was a major challenge. It wasn’t that the work was that difficult – it was trying to tackle the organization. Did not help his cause by refusing to get help from campus resources. Took a semester off to regroup and still struggled afterwards.
He loved IB and got a great education, but if I had to advise him on making the decision again, it would have been a different one. He gave a lot of thought to his choices, and I know he picked the one that he liked best (and we thought it was a great fit, too), but the workload was daunting and the lack of institutional support very surprising compared to the STEM program.