I found this interesting video where a driver compared the streetable power of the Hellcat and Scat Pack. He tested them with stock and MT tires doing 0-60 mph runs. As expected the times greatly improved using the MT tires, however, only half throttle could be used on the Hellcat. The verdict? The Scat Pack is the better choice for the street.
While I agree the ScatPack Shaker would be my choice for style I say you can never have too much power. You just need to learn how to control it and your temptation to use it. If you want and can afford a Hellcat, buy it.