I think it would be short-sighted if not ignorant to go with something like an 8320 for a system with a higher end GPU. not only are you going to limit its performance now it leaves you really nothing to upgrade to without really bottlenecking the crap out of it. if you can't afford a 4670 or 4770 to go with the system that's going to use high end gpu then you should wait until you can afford it. Gimping yourself on day one and killing future upgrade performance is just stupid in my opinion.
For a gaming system with a single GPU (even a high end one), an AMD chip isn't going to bottleneck much, if at all. I could see the logic there for someone who's on a budget and can't spare the extra $100 or 150 for the Intel chip. I mean, if you wanted the best possible gaming performance at X budget, it's hard to argue with a GTX 780 over a 770, because the GPU is much more important for games than the CPU. Sure, future upgrades are something to take into consideration, but if you had to stick to X budget and wanted the best gaming experience you could get right now at that budget, then I would argue GPU takes precedence.
Granted, once you get out of the "budget gaming" range, it's increasingly hard to justify an AMD build. Getting a good overclock out of an FX chip requires a good cooler, which can easily add another $50-100 out of the price.