We see alot of supercharged domestic cars and i can tell you now most of them (vortech style) are laggy dyno queens, the twin screw are the only way to go.
i should post some boost curves from vortech, kenne bell and harop chargers vs turbos... you will be surprised.
My thoughts on supercharging fall into two groups, dyno queen or useful I prefer to use a whipple (twin screw) style setup as boost is more turbo like ie comes in and stays constant whereas your vortech style charges increase boost with rpm so peak power and boost is always @ peak rpm... great for dynos, crap for daily livability.
The whipple will hit target boost quickly and offer FAR GREATER area inder the curve, much like a turbo setup.
Here is a comparison boost curve vortech vs turbo
Here is vortech versus whipple supercharger.
Twin screw --->
Vortech --->