PlanesPete,
It is nice to have a super dupper alarm,but have you thought about what you will be able to do when it goes off and you are near by ?(unless you live very near to the cop shop and they are not havine a siesta)
We had an incident last summer when 3 or 4 itinerant workers decided to walk across our place looking for the neighbouring farmer, who owed them money.They were not in very sociable moods and I dont think the iron bars they were carrying were for swatting flies !
Police never attended that day and probably never did.