There's an article here that discusses the use of multiple subs and that doing so would theoretically provide better results than using just one (I think it also assumes multiples of the same sub are used). The article includes a link to a white paper on the topic that can be found here.

Getting all those subs dialed in might be difficult. Whether it's worth it to go to all that trouble would also depend on whether you are looking to get great sounding bass in multiple locations throughout the room or just for the primary listening position.