IS-F vs a 2011GT = no brainer. Sure they are close in power, but you are also comparing $60k to $40k, which makes no since once you go past the power of the cars.
Price wise you are comparing an IS-F to a 2011 GT500, which is pushing 550hp and 510Tq, no contest in the power.
Quality has always been a no brainer for Lexus, but a lot of this posting goes to show that very few have not noticed the boost in quality Ford has done with the Mustang, both inside and under the hood. They are in no way up to Lexus standards yet, but then again, Mustang has NEVER been a luxury car and never will be, its pure power, its a MUSCLE car, not a Luxury Sports car, 2 different classes of cars.