Eric, the 570 is a nice center. Don't spend money changing it. If you feel you must, go 160v4. Forget the 150. Axiom (thankfully) discontinued it. I love the sound from my 160v4.
Spend the money on QS10s and a sealed sub instead. Trade in the QS8. Mount them to the sides and not behind. Our ears are far less sensitive to sounds from behind. Don't mount them to the coffee table. Get ceiling brackets from Axiom and dangle them from above.
Did you find out if you have v4 M80s?
P.S. Have you tried running your speakers from the 3500 only? Any difference over the 2300?
