I bought the Shield 9 NTS early this year. I've been shooting the majority of my life and was trained from the start that a manual safety is only a backup to safe gun handling. If you obey the gun safety rules then you already know that your finger never, ever goes inside of the trigger guard until you are ready to shoot. With that in mind, the design of the Shield will not allow it to go off unless the trigger is pulled.

My wife who really hasn't done much shooting until the last year purchased the Shield with thumb safety because she felt it would be safer. She got her CCW back in March and has since taken a couple defensive handgun training courses. This has taken her shooting skills to a whole new level and she now carries her Shield with the safety off.

As others have said, it's really personal preference and in the end only you can make that decision. The Shield is definitely an excellent carry gun. It's lightweight and small but shoots like a much larger gun.