Gov: I am thinking since your son has time, he should take both the SAT and the ACT. It definitely seems ACT has been the more recognized, but SAT just revised their test to be more like the ACT. If he is striving for the high academics, having excellent scores on both tests cannot hurt and may actually help if he is right on the border.
We are also finding some of the schools also value the SAT subject tests, particularly if he is thinking of a STEM major. As we have been told, the subject test will not hurt but a great score can really help on a technical subject like Physics and Math. Chasing a baseball dream at a high academic school is challenging and the coaches and the schools want to be sure the kid can handle the demands of both.
Good stuff... Even if you have just the ACT, for some of the high academics don't you have to take two SAT Subject Tests? Others here likely know, have to look that up... Think son is leaning on the financial-economics track...