See AN1018 for a discussion of replacing reed switches with Hall effect magnetic sensors.

• Hall effect sensors are generally more rugged in terms of shock and vibration
• Hall effect sensors are surface mount compatible
• It is much easier to detect tampering with the Si72xx series of hall effect sensors
• While a reed switch is inherently zero power, less expensive SPST switches require a pull up resistor which consumes about as much power as the Si720x series of parts sampling at 5Hz