I'm looking for the original study I saw. I haven't found it yet, but here's one that found that trackballs were superior to thumbsticks, even for users familiar with gamepads and not trackballs (hardly a revelation, certainly, but you'd be surprised how many people contest it): http://www.yorku.ca/mack/FuturePlay1.html

But come now, my original statement was hardly all that bold. Obviously the reason that gamepad aiming sucks is just that thumbstick aiming sucks. Replace the thumbstick, solve the problem. (And as a bonus, get analog movement as well as analog aiming--the traditional WASD doesn't allow for speed gradations.) I used to game exclusively with a trackball and never had any troubles. The only reason I stopped is that nobody makes trackballs for left-handers anymore that are any damn good. And if you don't believe me, I just gave you a couple of quotes from gaming professionals.

There is a large difference between CoD and CS. That's what you would have to convince me with... that or SC.

I'm pretty sure CoD and CS both involve aiming a crosshairs. That's the only thing that's really relevant to this discussion.

As for Starcraft, you're right, it wouldn't work; not because of the pointing device, but because a gamepad doesn't have enough buttons to manage all the hotkeys. In my original post, I called out FPSes specifically for that reason.