Whelp, finally decided to retire my venerable Tank007 E09 keychain light. I got the light the first week of January 2012 and it officially went off the keychain on Friday, marking nearly 22 full months of use. In that time it's been dunked in lakes, run over by my car (by accident, I swear), taken on trips, lost in the yard a few times, and generally used, abused and beaten up.
And after all that? It still works exactly as well as they day I got it. The threading is smooth and easy to operate, the glass is free of scratches and the light hasn't had a single malfunction, issue or problem even to this day. I retired it only because I wanted to try something new.
To be honest, I quite like the light I got as a replacement (Bronte RA01), but the Tank007 was much easier to operate one-handed because of the excellent knurling on the head and softer spring tension. The E09 also has a noticeably brighter high mode, even if there was a considerable cost in terms of battery life. The Tank could also take 10440s, which the Bronte can't.
If anyone is on the fence about trying one of these out, I highly recommend it as long as you don't mind PWM (not noticeable to me, but noticeable to some) on the low and medium modes.
Here's to you, buddy


And a family portrait of the keychain lights:

Mr. Like KC-05 (awful UI)
Tank007 E09
Trustfire F23 (too heavy for a keychain, good light though)
Bronte RA01