I was just approached by someone who bought one of these lights last night and I'm not really familiar with them.
As many of you have experienced, the O ring on the back did fall apart as soon as the tailcap was removed (replaced it with one that came in the box.)
My question though is whether or not it is a normal characteristic of this light, that the tailcap has to be screwed all the way down (pretty tight) for the switch to work. Seems that this one has kind of a LOTC in that the moment you move the tailcap the slightest, the contact/circuit with the battery is broken. Additionally, I noticed that it flickered a few times from dim to bright though it seems to be okay right now. I'm not sure if this one is a dud.