I had a meeting at CES with a group of Acoustic consultants that get together know as the "Acoustics Guild". Most of us do Home Theaters. The overwhelming preference was for three or four subwoofers. From a "solutions" standpoint, we have all found this to work. I use four smaller subwoofers rather than one big one, so placement is not such a big deal.

But then again, even a lot of woofers won't cure a room with insufficient LF damping - got to get those modes damped down first! Then you can start to talk about "bass quality".