I replayed DMC4 and I noticed that it was 3 shots but the animations did seem a bit faster.
Also I hope its done like how Rainstorm is done because pressing X + A/square + x because due to how your thumb is on the controller pressing those 2 buttons together are the easiest button combination....I play Tekken trust me X+B/square+triange is a pain to do compared to X+A/square+x. It will be very frustrating to shift your thumb, nay your hand, so it be inline to for that type of button combination and for a fast paced action game like this it will be quite a pain to pull off but for a fighter its a different story. Due to how the controller is set up and how your thumbs and hands are on it the Y+B/triangle+circle & X+A/square+x button combinations are the easiest to pull off especially for games like DMC but A+B/x+circle is though not as good/comfortable as X+A or Y+B but its still slightly better than X+Y.
However, diagonal button combinations such as A+Y and B+X is a different story.