The implementations are certainly convenient -- you don't have to panic quite so much if you arrive late to the football game. At the same time, it's hard to avoid the privacy concerns that come with Precheck and biometrics. Is it worth handing over personal information (such as fingerprints and your Social Security number) just to be sure you're in your seat in time for kickoff? And if enough people sign up, Precheck could lead to a pseudo-blacklist where those who refuse to enroll are effectively at a disadvantage or treated with suspicion. This doesn't mean that Precheck at stadiums is a privacy nightmare (Idemia promises to keep info private and secure), but you may want to consider how comfortable you are with data sharing before you rush to sign up.