Any good security solution should have a cellular backup, so I wouldn't worry about that too much. All security solutions are going to risk for the same things - someone disconnects power/internet (hence cellular backup & power backup), defeat of sensors (not much can be done about this other than ensuring they are placed correctly), or knowing the password/defeating the device. I wouldn't worry too much about someone hacking the wifi, as long as you have a strong password, however you can certainly defeat most of the wireless devices out there by using a simple radio frequency blocker. If you are really wanting the most secure option, I'd simply focus on having wired sensors rather than wireless, or at the very least you have a system that defaults to alarm / notification if it loses connection with a sensor.
Generally most security systems are defeated because A) the response time is too slow, so they just allow the alarm to go off and they can get in and out quickly enough that it doesn't matter or B) the attacker knows the door code, or a method to get in safely.
Unless you are a target, most attackers are going to do a quick smash and grab, they won't be casing your place and figuring out how to defeat your security.