Do France beat the US...
I have been informed that at least 2 French manufacturers (DIATEM & DIAGRAL) have designed theyre wireless alarm system receivers and transmitters to operate on "dual frequency" on "dual bands". Even if it don't solve (can't) the RFI muzzling problem, at least it "may" minimize them.
This require that two individual receivers are used (?). I still like to see theyre specifications, its maybe just sales talk without ground like usual in the US.
In the mean time, wireless are still unreliable during Radio Frequency Interferences (RFI) and nothing cant prevent those external transmitted signals to be there. The worst is that when your system is dead, it don't warn you...
Wireless Alarm Systems = Illusionary safety.