Having used cheaper versions (Floodstops), I'd always worry about false alarms caused by, say a sweating toilet, when my wife is in the shower and I was not at home. Probably unaware how to dry everything off and restart the water, she'd be without water until I got back.
So I ditched them. They went off a few times at night after a steamy shower as well. Waking everyone up with the alarm (if fitted).
The only one I do keep, and not a cheapo like the Floodstops, is a Watts intelliflow on the washer. That seems like a good idea. Until it breaks anyway.