Putting absorbers on the side wall at first reflection point is actually 'old school' acoustics...
...SMT stands out with their S- and V-wings. These wings do not only diffuse the incoming sound waves, they also introduce - and that is unique - a time diffusion. Both combined explain their effect. Suddenly the room becomes (virtually) much bigger, the soundstage widens a lot but without loosing focus, on the contrary! The time delay causes the sound to be experienced as being 'richer' as our brain adds the delayed incoming waves from the wings to the original and this causes this effect.
...If you want a first idea, before going crazy, of what the SMT can do: buy one pallet with four wings, put two on the first reflection point behind each speaker and two on the lateral reflection points, if it doesnt amaze you, you will stay away from them, simple! But you will be amazed and start thinking how many would fit in your room, don't be alarmed, join the club