Back to the sub issue, I ran my M22 system with a very old Costco special D-Box (they make butt shakers now) sub that filled in the low end good enough to keep me happy till I could afford a much better sub. 4Yrs later and many sub auditions later I finally bought the best one I could afford. So I agree with you Papa, you can most certainly wait if your current sub will at least be contributing to the new systems overall sound, but once you start looking at the newer higher quality subs, you won't want to go back. Now buying the QS4s would allow you to start saving up for that newer, better sub and not have to wait 4 yrs for it like I did.
