We have both a 2006 Viper Coupe and wifes car is a 2011 911tt and it's her DD. Not her first P car. The 911tt is a nicely refined car, fairly comfortable. It's very quick 0 - 80mph. But after several years experience with various P cars I'm FIRMLY of the belief that you never, ever own one of these without a warranty. You could buy a nice GenIII Viper for what it will cost you if that engine has an IMS failure which is fairly common in older gen engines. The newer 9A1 engine has no IMS. Reading the P car forums 2005 was a bad year for engines.
As for handling, the 911tt gets a light feeling on the front end at / above 80mph, something you have to get used to. It definitely doesn't feel as planted as the Viper. Don't misunderstand, it does corner, it has the infamous under steer due to the AWD, it just feels light. You have to get used to the e-throttle delay and there's no power at all below 3500 rpm, you have to wait for boost, and that comes on all at once. It's far easier to drive a Viper smoothly and fast. P car is loaded with nanny tech that you can never completely disable. The electronics are an absolute nightmare. Manual trans is several decades old tech and works very well, but the cable shift has a feel you may need to adjust to.
Wifes impressions are really funny. We have a 2009 Challenger SRT and she prefers the clutch, shifter, steering and brakes in the Challenger. Steering feel NOT handling. She complains about the blind spots in the Challenger [and the Viper ] .. P car has good visibility for her.
Oh, and the Viper gets better mpg's too ...
Good luck
--FQB