I'm very pleased with how this one has turned out so far. We've got a good sample. The overwhelming majority is ambivalent to the button, or as sonic370 said, "I'd rather have it and not need it than need it and not have it." Second to that, a lot of folks just don't care for it. But there is a group of people who find it useful, and even some who don't find it useful have cited times when they've used it.
There's also a decent number of people who want bad things to happen to me.
I also learned that Belgian Z's don't have the panic button, and perhaps that's generalized to greater Europe??? I don't know. But that was interesting to learn.