I have a pair of old SF-1s with b&w surrounds, a polk subwoofer, and no center. I am pretty sure I am going to upgrade to a full F-3 setup with F-3 mains, C-3 center, S-3 surrounds, and a sub-12 but i wanted to make sure this is a worthy upgrade. I am not able to afford anything more than the F-3 speakers and I am going to keep my Yamaha RX-V520 receiver. Will I hear a very big difference? Is it worth the money? Thanks, Jake