I have a 2010 Grand Sport with the NPP exhaust with a dealer installed Mild-to-Wild Switch. While it is a very easy plug n play switch, the dealer where I purchased the Corvette always installs the Mild to Wild switch. Two obvious reasons, it is cool, and they make money on it.
With that said, I would NEVER get a Corvette without the NPP, now that the option is available. It eliminates the need to buy any other after market cat-back exhaust system, if one chooses to upgrade performance, or want a better sound.
If I am going to church, or before 9AM, or have a headache, I leave the switch in normal operation. I don't use the radio, as the burble over run sounds awesome with the wild exhaust (butterflies open).
I have never had a problem with local or state police. It isn't THAT loud unless you are on it. If you are on anything, including a Prius, yes, it does make noise.