It depends on the way you have fun in this game.
For people that are always looking for 1 vs 1, 1 vs 2 fites, ACM is CRITICAL.
For people like me, who have fun killing the most, the better, and not dyieng is critical, SA is essential. When SA fails, then you have to use your ACM to defend your virtual life. The problem here, at least for me is that the most you use your SA, the rustiest your ACM become.
For what I have seen in the MA, and the results he gets , I could say that Greebo is one player that uses both ACM and SA altogether in the same sorties at excellence levels. (I've always seen Greebo in the "red side").
(S)