i tried another contact sensor (sonoff) before trying out the aqara/xiaomi sensors - holy crap what a world of difference in build quality and response time.

I have one in our postbox flap to detect when we get mail - the sonoff needed 2-3 seconds to detect anything being open (and thus would miss the event) - and the flap being closed by then made it harder to send out the signal. The aqara's are almost instant and send out while the flap is lifted.