Thanks for your reply Ian.

Let me see if I can now summarize what has just been said.

In an ideal world using any pair of speakers, the object is to create a realistic soundstage with a proper image without being able to determine where the source speakers are located.

With that said, this is easily accomplished using quality front speakers, yet it is much more difficult at the rear locations. I am assumming this is do to the distance that the listener sits from the speakers???

So to accomplish an Ideal 5.1 setup(ignoring the center in this discussion): You would want all 4 speaker to be an equal distance around the listeren to fom a rectangle, where the front speakers are as far apart from each other as they are from the listener and the same would apply to the rears (two equilateral triangles where the listener is the common point between the two trinagles).

Now this would be ideal. Unfortunately the average person doesnt have this kind of real estate to deal with. so what you are saying is that the quadpolar somewhat diffuses the rear signals to make pinpointing the their location during listening more difficult?