I really like the XT11 too, its my EDC now.
For me, I've watched, and maybe the light hasn't gotten hot enough, despite it being used for a long time at a stretch doing investigations...but I can't see a drop myself...so whatever it is, its subtle. I did note from instrumented tests that its not like it clicks down like a 3 way bulb in a desk lamp, etc...when they ramp down, the circuit apparently takes it down a slow ramp. Perhaps that's why I don't see it happening.
Anyway - Its a great light, with my favorite UI - a simple on/off button, that comes on in high, no matter what...with momentary, and a second button to change the brightness. A nice low 10 lumen low, a 150 lumen medium and 600 lumen high....and a nice floody beam that can still throw.
I also have a Zebralight SC600 in my pocket, which is ALL flood...but 750 lumens. I had some noise to check out at a park I was in, and the SC600 showed me a light pool of light maybe 60 yards around me...but not what the noise was.
Clicked the XT11, and there was the herd of deer ~ 250 yards away.