Ravi, who are you kidding ... "should I upgrade ...?" You can only fight the compulsion for so long. The answer, of course you should!
Will it make a difference? Yes, especially when you put your ear up against the back surround speaker.
I don't remember the rest of your system, but whatever you're using for side surrounds, unless they're QSx's, you should take one of them and put it in the back surround position. Take the other, wrap it nicely, and put it in the closet. Buy a pair of QS8s for the side surround positions. You'll feel better, in some ways, weird, in others. You will hear a difference.
