Just bought the GWM 5610U-1C. It was a tough decision choosing between the DW5600 and this, ended up choosing this because the atomic time keeping is cool.
However, I’m a tad annoyed that the time doesn’t perfectly match with time.gov and time.is since the atomic sync doesn’t account for time propagation, so there’s like a fraction of a second delay that’s noticeable. Other than that, the watch is fantastic and has most features I would want. (I wish it had barometer and altimeter stuff, maybe even compass, and dive rated so I can press buttons underwater)
NTP accounts for latency.
NTP is actually pretty interesting, here is a computerphile video explaining it: https://youtu.be/BAo5C2qbLq8
I wouldn’t trust a cheap radio controlled wristwatch more than a NTP synced computer that’s synced to a good NTP server.
P.S I have the same watch and it does sync pretty damn well with time.is