Our performance results were not too far apart in most of our gaming between the Radeon HD 7950 w/Boost and GALAXY GTX 660 Ti GC at high AA settings. We often found both video cards with fewer than 10% performance difference. We saw a few instances where the Radeon HD 7950 w/Boost was faster, and we even saw a few instances where the GALAXY GTX 660 Ti GC was faster at higher settings. So much for the extreme memory bandwidth advantage on the Radeon HD 7950.
So what does it all mean? It means that there is more to performance than just the width of the memory bus and the bandwidth available to the memory. There are other factors involved that determine gaming performance, and the widest memory bus with the most bandwidth isn't always going to be the winner in actual gaming performance.