Re: I haven't had an alarm triggered by toast for 10 years
Well the reason it needs firmware updates and connectivity is because it's more than just a smoke and CO2 detector, it's actually a secondary sensor for the Nest thermostat unit which adds additional ability to detect where you are in the house.
The idea is that you have one of these upstairs and the thermostat downstairs, so the thermostat can see you leaving the house downstairs in the morning, and the smoke detector can see you going to bed upstairs in the evening.
Another feature is the CO2 detector can shut down the boiler when it detects high levels of CO2, which is somewhat useful.
There is also the night light feature which puts a light on if the sensor sees you walking under it at night, or if the smoke alarm is going off.
So yeah the real reason to have one is simply to add an upstairs sensor for your Nest, the smoke alarm feature is great, but somewhat overkill if you're buying it just for that one feature. I doubt anyone is going to replace all of their £5 smoke alarms with these £120 units, I think the most likely scenario is that you keep your downstairs smoke alarm and maybe reposition one of your upstairs smoke alarms to make room for the Nest sensor.
Personally I can't see the issue with the alarm being able to be deactivated by accidental waving. The idea of a smoke detector is to wake you up if you're sleeping during a fire. If you're waving, you're awake, whether or not you're waving intentionally seems kind of irrelevant.