Andrew, I have the W22 and W150 (in/on wall) same as Potatohead. I also inquired about multiple 150's with Axiom when I was piecing together my system. In short, the 150's are designed to be horizontally mounted and do not reach as low as the 22's so are not recommended for L & R channel use. In fact if you could have a vertically mounted 22 for the center that would be the best bet - 3 identical speakers across the front - that's just not practical for 95% of us.
FWIW my in/on wall W22's do play down to 80Hz easily (I have verified with test tones and SPL measures) and integrate very well with my EP500 sub.
