Well, I've finally got the flywheel installed, and I must say this: I *LOVE* IT!!! Throttle response is awesome! A whole bunch of people were saying that my combination of the ACT Xtreme Pressure plate, Performance Street Disc, and the ACT 8.4 lbs flywheel would be completely un-drivable on the street. One word for all those people: WRONG! The clutch is very grabby, and the pressure plate makes the pedal really stiff, but it is definitely a joy to drive. It's not much more difficult to drive in stop and go with this combination. The idle is still really smooth, so obviously the lightened flywheel is still providing enough inertia for daily driving.
A lot of people also asked me why I would choose a performance street disc with the xtreme pressure plate. They recommended the 4 or 6 puck racing clutches. However, this is a daily driver, and those types of clutches are definately not very streetable. Also, you still want your clutch to be the weakest point in your drivetrain so that you don't start breaking transmission components.