in reality, whichever video card you purchase your gaming performance will be more than sufficient. sure, the hardcore gamers want the best but the best in the gaming market is usually close to overkill.
as for Nvidia, it's possible that their unified drivers are becoming the bottleneck. it's nice to have a single driver set for all cards, but shouldn't they just make a cutt-off at some point and optimize the drivers for a smaller group of chipsets. plus, it would shrink down the size of their drivers too!
as it is, their current set of drivers is over 10MB.