For performance of the different leds, you can check my test from March this year: 4 more 365nm UV-leds tested
@Mark, as a Nichia alternative, you can also check the Seoul Viosys led sold at Kaidomain, it has a smaller die than the LG led and is way less sensitive to overcurrent than the N.276A.
Funny that in actual use in lighting up minerals, overheating of the flashlight becomes a real problem even though the led can can handle that heat, it is something generally not regarded as a problem here on BLF where extended use usually does not occur. 