You're missing the security of calling the cops. Your system won't have that. Noise-makers are the "easy" part of security (they sell off the shelf ones for pretty cheap, no need for homemade).
No, I had never had any false alarms prior to this one. I live in a moderately sized suburb, not Detroit.
The utility of calling cops is vastly over-rated in most parts of the United States due to police response times being slow.