Update: Exactly 1 year from purchase and initial synchronization, the watch is +1.9 seconds ahead of NIST time. Pretty damn fantastic. Will be interesting to see how the accuracy and thermocompensation hold up as the movement ages. I didn't take measurements very often throughout the year, but from what I could tell the rate of deviation definitely slowed down during the cooler winter months.
Citizen's A010 and A060 calibres (rated at ±5 sec./year) perform TC correction roughly once every 24 hours, compared to ETA's PreciDrive movement which does it every 16 minutes. Presumably the Citizen movements have larger correction intervals to save energy, since they are solar-powered. I haven't checked the accuracy in different positions; Citizen's newest 0100 calibre (rated at ±1 sec./year) uses an 8.4 MHz AT-cut crystal with negligible positional variance, but the older A010 calibre uses a 32 KHz XY-cut crystal that can vary by up to 2 seconds a year in different positions. Outside of Hoptroff's CSAC watches which each contain a miniaturized atomic clock inside, you won't find watches more intrinsically accurate than these.