Anotn,
First and foremost, it's my humble opinion that you should consider your supercharger choice based on performance goals, not simply based on sound.
That being said, if you like the sound of the 03 Cobras, then you'll like the sound of the Roe blower. Roe basically uses a Kenne Bell 2.4l twin screw blower. Quiet at idle, but screams at WOT. Paxton is a centrifugal blower. Whistles more at idle, but not quite as prevalent at WOT.
The Roe twin screw blower is a positive displacement blower, meaning it forces the same amount of air into the motor with each revolution. It is a direct replacement for the stock intake manifold. The pros are: boost and throttle response are immediate, there is no "lag" and boost is not rpm dependent; torque numbers are generally higher on a twin screw setup than its identical centrifugal counterpart; you don't have to run the car to redline to make killer power; more power down low in every gear. The cons: because it replaces the intake manifold and forces air directly into the motor, there is no way to intercool it (however, you can run a water/**** kit which acts as a "chemical" intercooler); the peak horsepower numbers are generally lower on a Roe setup than a Paxton setup on a pound for pound comparison. However, it seems like there is more power under the curve on a Roe.
A centrifugal blower is more like a turbo in application (although it's belt driven, not exhaust gas driven). Boost is rpm dependent. The higher you run the car, the more boost the blower will make. Pros: the centrifugal kit can be intercooled. The basic kit uses a air/water intercooler, but the tuner kits use a big front mount air/air intercooler. The peak hp numbers are generally higher. Cons: You have to run the car to redline to really take advantage of all of the power (because boost is rpm dependent). Centrifugal cars generally make less torque than HP (and less torque than the twin screw counterparts).
Both kits cost "roughly" the same. A Roe kit with water/**** will run you around $8K, plus installation. A Paxton basic kit will run you around $9,995 installed. They end up pretty damn close in price. The Roe might be a tad cheaper. I will tell you that the VEC2 is a great tuning tool. Much better than the Split Second box or no tuning computer at all.
This is not an all inclusive article on blowers, but I just thought I'd try to throw out some very basic points to get you started.