I had the S2 Index for 5 weeks, twice did it drop readings.
They simply never made it to the backend / Connect app.
The strange thing is, that if you deliberately tamper with the network, do some readings, and then fix the network, then it syncs, as it is supposed to.
But approx. 2 our of 80 readings, including my morning reading today, was just lost into thin air.
This automated syncing of data, is the ONLY reason I spent money on this scale. And upgraded from my old Tabita with an SD card.
Making a 100% solid sync protocol that never miss any data shouldn't be difficult for such tiny tiny amounts of infrequent data.
While all the other data and gimmicks are fun, then I doubt that it is the real reason people buy a fancy scale. It is the data you get in Garmin Connect, and frankly, I think everybody expects that to be 100% reliable.