Axiom Home Page Forums General Discussion Home Theater Center Channel upgrade advice. vp180 or m80

I have almost completed my 14x25 Dedicated HT with a 147"AT screen. LCR speakers sit behind the screen so I can put anything I want back there. I currently have
2 M80's v2
vp150
2 QS8's v2
I want to add a better center and it has been suggested to me by some to just add another M80 rather than a vp180. Long story short they seem to think the vp180 has design flaws....what do you guys think?
Would you suggest a separate amp currently using a Marantz 7008.
also I want to add rear channel so i would assume 2 more QS8's or should i use a direct style speaker. They will be mounted 4ft. behind seats with the current QS8's along the sides.