Jim brings up a good point here. There are barometric pressure sensor limitations with any altimeter. Altimeters using high output level MEMS barometric pressure sensors will flat line at some altitude, typically corresponding to between 25 kft to 45 kft altitude depending on on-chip and external electronics. It not the MEMS pressure sensing element that cause this limit, but the internal IC amplifier circuit that was poorly designed several decades ago.
The sensing element itself is good to 100Kft.+ (130 kft as an apogee sensor) and several vendors, including Adept, build their own log amplifier circuit to take advantage of the large dynamic range of the unsimplified MEMS sensor. Using an external amplifier circuit is more expensive than the high level sensor, and not required by most folks, but if your going higher than 45Kft, your apogee detection options are limited to external amplifier MEMS pressure sensors, GPS, or inertial sensors.
Also there are two choices that can be made by logic when a sensor flat-lines: fire or do nothing until you determine you are really on the way down. The problem with the second option is that if you go way over the limit, you're coming in too hot to deploy anyway so.... More expensive units like the R-DAS, ARTS, Parrot could be programmed to use the barometric sensor in concert with an accelerometer and a time to deploy under more than one condition, and indeed the R-DAS (an probably the others) use the accelerometer at the apogee detector, and use the barometer only to fire the main.