Also, I must sadly report that my very first A2 is starting to show signs of wear with the 100+ rings I've put through it. Went to test KD's ring and it didn't work when I twisted the tailcap, but did when I pressed it. A quick examination inside revealed the cause:
Normal tailcap spring (hovering over it's copper pad)
Think SF will send me another tailcap if I ask nicely?