I think that some folks percieve "lag" as "animation lag", and others percieve it as "crosshair lag". I don't see any "crosshair lag", and I know that the animation lag on my gun/character is just visual fluff to make the game look cooler (which I appreciate).
The crosshairs aren't laggy, and that's what matters for gameplay. Any visual lag just makes the game look cooler, which I am totally fine with, but I know some folks have trouble separating the animated weapon model from their virtual gun in games. Hence my stance -- user perception.
The gameplay lag (crosshair) just doesn't seem like an issue at all, and any animation/visual lag of my gun/avatar just doesn't throw me off (it does for some though) -- I hardly notice them, really, except that the more organic animation enhances the "you're there" feeling for me in SP, which is cool. If there was any real lag in aiming, I think I would probably notice. I play a lot of MP shooters, on both the 360 and PS3 (and the PC), and I'm a pretty darn good shot with a dual analog (if I do say so myself ;).
