I received the U1CUID update today. I checked and it was available. In US and Bluetooth Classic 46mm version. Update was 101.33 MB.
Nope, though to be honest I really have not noticed any difference after the last 3 updates (2 in Sept. and 1 in Oct.). I have had zero stability or reliability issues since I got watch (pretty much at launch).
What does it say in "what's new" description in watch update settings?