The first few dings, I'll be feeling like a fool and concerned about breaking it. The first ding is a flaw, but after it's survived a few, the additional marks take attention away from the first cosmetic flaw and they drift over into character and evidence of durability.
The excellent UI is what really sold me on these lights, it's the kind of UI that I always wanted but gave up hoping for, great work Tom E and TK.
I've noticed one ironic glitch/feature, which is that the lockout mode does not survive in memory if the tail cap is loosened and tightened, even for a second. This limits the usefulness of lockout for me, but I can see how it would act as a fail safe for someone who didn't know or forgot about lockout.
However, the momentary only mode is retained even with the tail cap loosened for an hour+, I haven't tried a longer duration yet. So momentary is going to be my default lockout.