I bought one of these for that extra little piece of mind.
Installed on my gate. No it does not rattle or make any noise of any kind, it comes with velcro tape that keeps it from moving around and makes it impossible to remove the gate even if they defeat the factory lock. By the time they get done breaking the factory lock and then see that thing, they will likely say screw it and go find someone else's gate that has no extra protection.
Yeah I have full coverage insurance but I'd rather spend $14 bux on that little deterrent than have to pony up a $500 deductible.