Absolutely worth the extra cost

But one expects times exactly, saves you the purchase of approximately 11 9V batteries, and the smoke detector may even be used twice as long as other detectors.
Normal Smoke detectors should be replaced after 5-6 years - the PX-1, however, saved only after 12 years = 1x initial purchase. Then one is with the 12-year warranty even if times a defect occurs on the safe side.

The whole then tops only a magnet holder from the high-end segment. Pull film - stick holder to the ceiling - detectors hang - finished.

Here everything has been covered. Also, the test alarm is not as annoying as in other detectors. Here only a brief signal is issued. Other detectors I test only not because you have to then are afraid to be deaf.

I had actually considered this indicator to be used only in the kitchen and to buy for the rest of the house "cheap" wireless detectors. But after I have now recalculated times it is much cheaper rather 1x to pay a little more, as after spending extra money for batteries and replacement indicator.

Soon there will be from the PX-1 is also a wireless version. Since I will have immediate access and supply the rest of the house.

Update 03/13/2015: I have left at a smoke detector of this model for the kitchen, other customers mention here very often false - and that's risking too delicate.
For the rest of the house, I use the detectors which have performed well in a Warentest magazine (Ei650). With whom I am very satisfied - except that the radio version is way too expensive for the time being and I renounce it.

The PX-1 has triggered even 2x justified (beeps very "relaxed" I think, you take it in the first few seconds not immediately as a fire alarm true (was only light smoke the microwave .. burnt popcorn)). But also has advantages when it is not so a "panic alarm" triggers, so all the best :-)