What's interesting is the 2011+ V6's put out almost as much power as the 2005+ 4.6L, and last I checked it was a V8. Match one of those up with a 2011+ V6 (with gears other than 2.73s) and it's pretty much a drivers race. That's when the close ratio gears of the 6 speed transmission give the V6 an advantage if both are matched up equally power wise.
The 2011+ GT's are great cars for their price point too. 400+ HP and even the base car can hit the track & put up good numbers.
What these new revised Mustangs have really done is put peeps behind the wheel who otherwise would have decided on something else. I wouldn't have purchased the V6 if it was still at 200HP, and I'm sure there are new people in 5.0's who decided on the GT mostly for the driving experience of a 400+ HP car.
While the GT undoubtedly is a better driving experience, in reality as a daily driver, there aren't that many times during a typical day when a driver can take advantage of that extra 100+ HP. Unless you live out in the country, desert, or hit the track often.