The 2011+ V6 Mustang is a great car, and with the Performance Package, it will out brake and out corner a GT. Track times still won't catch a GT, simply because the massive torque of the Coyote just out classes the V6, even as good as it is. (The stock GT beat an M3 with Randy Probst behind the wheel, it's a fantastic car.) However, the V6 PP is basically the same body and suspension with bits from both the GT and GT500, minus 100 Hp and 100 lb/ft Tq, and with a 305 Hp Ford/Mazda race-bred V6 under the hood, it is a visceral experience that can't be understated. It corners like it's on rails, the braking is highly confidence inspiring, and with a quality set of cans, the V6 has a very enjoyable howl of it's own, especially above 4k or so. It's simply a great car, and should be on anyone's short list of affordable performance sports coupes.
Is there a huge difference between the GT and the V6 PP? Fully loaded, it comes down to 100 Hp and 100 lb/ft Tq. What that equates to for you is entirely up to how you will use it. If you will be going to the drag strip or track a lot, think that any engine with less than 8 cylinders is doing it wrong, regularly need to evade Ninja assassins in a fleet of Dodge Challengers, and have to have the ultimate everything and you aren't willing to compromise, go for the GT. If you will be using the car primarily to commute back and forth from work, don't go to the drag strip, don't street race with Ninjas, don't need the latest ultimate everything, and have other life priorities, get the 2011+ V6 Mustang, preferably with the Performance Package. It's still one of the best sports car bargains available, and your extra $6000 can go into your 401k/College Savings/IRA.
If you're just trolling all of us to start a flame war, I think you failed.
2012 Mustang V6 Premium Coupe, Red Candy Metallic, MCA Edition, Performance Package Go:
Bama 93P Tune, Airaid MXP CAI, FRPP Sport Exhaust Show:
Suntek Carbon 35, GT500 Splash Guards, Redline Goods Shift and E-brake Boots