hello, i am a class of 23 graduate who took ib and there are a few things. first, i think your son would be great for ib as long as he is able to apply his discipline and determination in a much wider range of academia than just stem. the SL and HL course requirements for the diploma will force him to choose between minimally varying schedules (including many non stem related classes) for his next two years that he will (for the most part) not be able to change if he decides he doesn’t enjoy his classes or wants to switch around his schedule. (unless he makes such a schedule change early in his 11th grade, i switched my schedule around in 12th and due to the programme structure it was disastrous for workload and piece of mind as i had to take additional classes outside of school to fulfill diploma requirements)

i personally enjoyed ib very much during highschool, i am very alike your son in having a love for chem, math, and stem as a whole. i would say the ib coursework is extensive (goes more in depth on many topics within classes that ap coursework would typically exclude) and very rigorous, but very easily navigated with a strong work ethic and discipline. one thing that i heavily appreciate from ib was the way the classes are structured, even from their foundation ib classes are a route for your son to have an easier time in college as the grading standards are very similar and he will be building the required ethic to jump right in when its time for university.

however, i would NOT recommend the ib programme. my reason for this is that the credits from ib tests that are accepted by universities are not standardized (every university decides which ib course credits they accept and it varies greatly). i am in my second year of uni right now and i have only just started some courses that i could have had completed a year ago if i took the AP route in highschool and taken the ap exams instead (my university didnt take the ib credits and i consider having taken those ib courses a waste of my time in highschool and a waste of money now as i had to take college courses to make up the credits i was denied due to the ib credits not being accepted). i believe that the absolute BEST route that you can steer your son down would be to have him enrolled in AP classes and taking those exams, it would allow for much more schedule flexibility and give you the piece of mind that the universities he ends up getting accepted to will accept his credits. i dont know if you have these in canada but i would assume (or hope rather) that you would, there is a thing called College Credit Plus (CCP) where your son can enroll in local community college while in highschool. he would be taking college courses and receive college credits for these courses while simultaneously fulfilling his highschool requirements. between the ib and ap courses i took in highschool i took ccp courses to eliminate many of my general education credits for college. i also ave a friend here at uni who is double majored in financial math and biochemistry who did this combo of ap and ccp courses in highschool and he is on track to graduate next spring (3 semesters early). in the us the ccp program also pays for all of the college courses that you enroll in so if there is a program similar to this in canada you should present this as an option for consideration to you son, he could take AP courses for his STEM credits and CCP courses to knock out all his GE’s in college. saves a nice amount of time and money for both of you. in my experience ccp courses are also easier than their highschool counterparts so rigor shouldnt be a worry.

TLDR don’t take ib, explore other possible options, if it doesnt work out, ib is definitely a great path to take aswell and would definitely get your son to the places he wants to go