DS skipped over a year of Calculus with 5s on the BC test, and was always glad he did. One big factor for him was the strength of his precalc classes, believe it or not. He thought Linear Algebra and MV Calc were a breeze because he said he learned most of it in precalc (and this was public school). So your S’s foundation may be something to consider.
As an aside, my DS’ situation makes me sad that so many schools are into accelerating and then doing two years of calculus, instead of providing a more rigorous and more well-rounded foundation in math.