IMHO adding more speakers won't give the upgrade that adding more power, more power handling, better dynamics, flatter frequency response, room treatments, soundstage depth etc would add way more than just more speakers. 9.1 and 11.1 etc just seem redundant to me. A great pair of tower speakers might give the same sense of height, depth, and width within their own soundstage that 11 mediocre speakers might combine to do.
If "somethings not right", you ought to consider why it isn't right, and i doubt it's because you're not hearing the sound of wind coming from 3 feet higher. If I had something like 3 JTRs or 3 Seaton Catalysts or 3 RBH T1s etc as my front soundstage I think it would sound more impressive than having a 7 mediocre speakers dependant on DSP to even get some sound going to them all assorted in front of me.
or maybe i'm wrong. But really, i don't think stuff like PLIIz is worth buying a new receiver over. I'd rather spend 1000 dollars on a great trio of LCR speakers to use as a home theater foundation.