We have the one pad version - and have no problems at all. The only times it's gone off are when DS is laying longways at either end of the mattress (leaning against the head/foot of the cot).. other than that - it's been great. You can adjust the sensitivity (if you have ceiling fans or a room fan for summer - you'll need to test it as it can pick that air movement up as breathing!).

They're great. Nothing more to say, I reckon!