As Robert said, available now. You may need to look to find one, but S&W is shipping them.
Preserve:
I'm sure if you ask S&W, there is no way for this lock to activate without turning the key. Like anything, time will tell. It may prove to be reliable. Without testing in the "real world" you just can't tell. Manufacturers do a prudent amount of testing, and then they field their product. That's when the real testing begins. I'm sure this has been tested as rigorously as possible by S&W. Obviously, they are comfortable that it will work as advertised.
Buy one and shoot it. If a lot of people do, then data will be gathered.