Stating that, “Nest Protect alarm lacks dual smoke sensors Consumer Reports’ tests find that the Nest is not your safest option. “An exercise in frustration.” That’s how one of their engineers described the process of setting up the networking functions of the Wi-Fi-enabled Nest Protect. (The alarm functions worked right out of the box.) It was reminiscent of some of the challenges they noted during testing of the Nest Learning Thermostat, the company’s flagship product, which went on sale in 2011. But the cons outweigh the pros, and so they did not add the Nest Protect to their recommended list of smoke alarms, although they recommend it as a carbon monoxide alarm. Their top-rated smoke alarm is the Kidde Pl9000, $23, a dual-sensor alarm that was excellent at detecting flaming and smoldering fires.