how do so many people produce clean results, while I always struggle to do it right and there's always flaws in the materials and methods that make the results ambiguous :-( ......
Ok, I ran the dome/dedome test with the XM-L2 T6 3C I still had from the test of the OP. First thing that was not perfect was that the die had a slightly darker spot somewhere. It was not much, and I went ahead with the led:
I did a fresh voltage/output test up to 8A, and with the led still hot I went for the dedome. And apparently the led had cooled down just a bit too much, a bit of the phosfor had come off, say 3%:
Here's the dome with the bit of phosfor:
And the die at 0.5mA, if you look well you can still see the dark spot as well:
Yeah, more variables than I need: does this extra blue add to the lumen-count or will it reduce it? I have the impression that my luxmeter favors blue a bit too much, but perhaps still not as much as green. The 'blue' region of the die occupies about 3% of the die, does that matter much for the test at all? I don't know, so I just went on to the second run testing, and will just dump the results on the net for you to decide what it all means :-( :
At least the dark spot on the die did not get any larger in the course of these tests (I checked afterwards).
So... if you ignore the phosfor damage as a factor involved in the readings, dedoming gave about 10% lumen loss, and has no voltage effects (you see only one voltage curve because the two curve are completely on top of each other).
I think I may carefully assume, perhaps (*sigh*), that 3% phosfor damage could not have counted for 10% light loss on its own, so dedoming a 3C does lead to lumen-loss. The XP-L was a 2C which is cooler, and in the reasoning started by led4power in the above 2 posts, dedoming that tint could cause less lumen loss, because more light converts to the area of maxumum eye-sensitivity by the dedome.
So nothing can be ruled out for certain, jay!
(Not going to try this again, can I now just go back modding some flashlights, please? ;-) )