yea, i can confirm there is a SFO base. It started years back around the time CX went to 2x daily to SFO. The SFO crew regularly fly CX873 and CX872 (night departures from both SFO and HKG, respectively), although sometimes sub in on CX870 and CX879 and have standby. There aren't too many, if you fly CX873/CX870 enough you'll end up knowing half the crew on those flights so comparatively speaking I think it's a small base. Seems like a close-knit group. At this point I configure my SFO schedules to ensure I do CX872/CX873. Not only do you get guaranteed new J class in 77H vs old J in 74K on CX870/CX879 s but service is excellent flying with the same FAs numerous times. takes service to a different level when you're seen as a regular passenger on their route. i've flown with the some FAs on those flights perhaps 5-6x now.

CX North American headquarters is also in SFO, fyi. never knew exactly why but maybe it has something to do with cargo given SFO doesn't have the same CX pax throughput as say JFK or LAX