My wife and I just tested a:
4.8 with no Sport Package,
4.8 with Sport and a
3.0 with Sport.

We ordered the 3.0 with Sport.

Tracks like a train- indeed. She drives like Danica Patrick so she noticed that with the sport, the 3.0 drove better than the 4.8 without it. During the test drive we slamed the brakes at 70mph and the car barely tilted forward. No loss of control.
We gunned it and the car barely kicked back, the only noticeable sense of speed is the needle sweeping across the dash! haha.
Weaving in and out of traffic is a breeze and you can do it with absolute confidence and grace- and of course style.
Of course the 4.8 with Sport package drives like a bat out of hell and sounds like a beast but we just couldn't justify 2 more cylinders for our majority of driving. Not so much the price of gas but the hassle of pumping. Rather be driving! Ours comes in a few weeks.