I almost bought my first shotgun.
http://www.cheaperthandirt.com/product/GUN-982
But after tax & shipping it ends up being close to normal price for the gun I think, so I didn't. Also, CTD.
Re: M&P 40C, by S&W's designation, the C is for Compact. They call their compensated model the "Performance Center Ported". Tweeter might have meant something else, though, so who knows.