I think this is a great idea, and your results will be helpful to lots of people.

I'd like to suggest one change in your methods. I think you should set affinity to all cores, in other words, every instance of WoW should be able to run on cores 0, 1, 2, 3, 4, 5, 6, and 7.

Here's why. Most programs don't set their own affinities. In other words, they leave the operating system free to assign their theads to any and all cores, which gives the operating system maximum ability to optimize performance. This is the "real" default affinity, and it's the same as what I just said you should set deliberately.

But WoW isn't like those normal programs. For some reason, Wow takes deliberate action to set its own affinity to only cores 0 and 1. That means no matter how many instances of WoW you're running, it's restricted on a quad core to using (at most) half the CPU. It's the same two cores for every WoW no matter how many you run.

Nobody with a quad core should multibox that way. Obviously everyone wants their WoWs to make use of the whole CPU. But you're testing that way with just two virtual cores.

So I suggest using the "real" default -- the natural operating system setting -- for test purposes, with all threads free to run on all cores.