I don't think your right on that Sam. In the article that you posted, the bridge is listed as 2GB/s That's big B. Sata2 drives as well as sas drives are 3Gb/s theoretical transfer rates. Little b. So 1GB = 8Gb. So that gives us a 16Gb pipeline to the northbridge where the cpu, ram, and video are. To max that out you would need over 5 drives. Basically 6 in a raid 0 to cap it on paper (you would prolly need 3x this many drives to actualy cap it in real world use). Very very few people have that in a personal PC.

In my opinion that is not going to be a bottle neck for anything and maxing it out will only reduce load times during the start and entering an instance. You may see a framerate dip when you first get to Dalaran, but once the textures and stuff are loaded, I do not see that having any effect on performance running around Dalaran when everything is already loaded into ram. If your suffering performance issues in Dalaran then you either do not have enough RAM or you do not have your folders symlinked and are multiplying how much needs to load and wasting resrouces.