Haha, I remember standing there and saying "This is the point where you cheer and such..." and they were like "nhuh.." pulling up their shoulders... :)
The shaft can lag behind no problem, after all there's still server delay and it always gets worse if you have to swing the mouse around. But since it's Cooller shooting .. =)
I think having it large enough can help you visualize the amount of lead with hitscan weaps at some distance. Kinda like how I made custom crosshairs with marks to the left and right when I was learning quake 2 with 200 ping.
I've found it to be the opposite for me. I use a rather small crosshair and find that I lead better overall with it. To give you an idea of what I use: