My reflows are not much above solder melt temperature, that is ok, but I guess intl-outdoor uses a refow oven that does the reflow more careful than I do. If I remember well the emitter I used was from intl-outdoor as well and originally came already reflowed on a 16mm board.
I also think there should not be a large difference in soldering the board onto the pill compared to using heat sink paste.
Different emitters should not differ by as much as 15%, but there is some debate on varying output results from dedome to dedome.
I am almost tempted to send you my flashlight for a direct comparison, or just the pill and lens. But it would be a somewhat expensive way to solve the mystery I guess :-)