I have seen a few users recommend these and a search of the brand brings up a few subjects with these mentioned, e.g. [Release] Xiaomi / Aqara / Opple Drivers with Presence!
there are some complaints about falling off of Zigbee but no one yelling from a mountain top to not use, at least not what I have seen so far.
Hell for the difference of 50 dollars (original price vs sale price) I am will to experiment and see how I make out. I have made more expensive mistakes before. 
