Wireless really isn’t any easier to beat than wired, as long as you or your monitoring company keep up with the signal strength and battery life. The issue I have with SimpliSafe is more to do with the fact that it’s a pretty $#@! product in general. I always recommend people who want wireless systems get either the Qolsys IQ2 or the 2GIG GC3 panels. They are both high-quality wireless panels with all kinds of quality of life (Qolsys = quality of life system) improvements. On the Qolsys IQ2, for example, I have a camera at my disabled mom’s place in Tennessee and a camera in my living room in Louisiana, and I can see both feeds from my IQ2 panel by my entry door.
Both are great, but my preference is the IQ2. You can get the IQ2 on Amazon for $350, and the door/window sensors run for about $24 a piece. For the 2GIG GC3, you can get it on Amazon for $300 and I usually recommend using Hondwa Linear contacts, which run about $18.