upgrade my sound!!

I need some advice. I currently have a basement home theater system with Paradigm signature S series fronts and center channel. The rears are also Paradigm installed in ceiling. My sub is a single 212/SE. Its great, but I was considering whether I should replace it with two S/812s for more balance and sound. I would also be replacing the Paradigm signatures with newer Persona models, if that is relevant. My processor is a Marantz AV 8805. the power amp is a Audio Control Pantages G3.Thoughts?