My setup:
M22Ti mains, Polk Audio Center, EP-175 sub, Mzero surrounds.

My friend has a pair of QS2s he might sell me at a steal of $100 CDN...

Would these make far superior surrounds to the MZeros?

As for upgrades, aside from a VP-150 center, are the QS4s going to make a huge difference over the QS2s? I have a H/K AVR-120 receiver which is only 45 watts (H/K Watts) per channell...