In dolby PLIIx modes the receiver will send audio mostly to the center to keep the dialogue centered on the screen but will move the sound left or right as needed. It will do this for neo6 as well.
For music I like all my speakers getting used, so I listen in 6 channel stereo which is just the left sounds going to all left speakers and a portion of it to the centers and the same with the right side, it really fills a room up with sound.
As you stated I would suspect the biggest problem is the speakers, so wait till the Axioms arrive before coming to any conclusions as to which way to listen.
