With all the information that comes out of the center channel i truly believe you need a robust center to get the full sound picture. If you have room i would recommend the VP 160 ,many people have made this very upgrade and the results are always impressive. I have read that a vertical center is ideal but i find it gets in the way of my tv screen. A third M60 would theoretically be ideal but no many have that option.

DOG is GOD spelled backwards.
What others think of me is none of my business.
M80 V3 MY GLOSS Cherry