Nice compilation, but I suspect your luminance value quoted for the XPG3 (and possibly others) is too high. Often the luminance is calculated by measuring the intensity above the LED (in candela) then dividing by the die area. But if light is being emitted by area other than the actual die than the calculated luminance will be inflated. I showed this with the XPG3. In these cases measuring the resulting beam center intensity from a flashlight and dividing by the reflector area is a better way of determining the luminance since, if properly focused, this method measures the light coming from the die itself. This phenomenon happens with other LEDs, too. If you look at the lit LED and see light coming from parts other than the die than the above luminance calculation will be inflated. This stray light is contributing to the total output from the LED, but contributes to the beam corona rather than the beam center intensity.