I dont know the answer to most of your questions.
they have generated an interesting conversation.
I presently EDC a single sw45k LED in a flashlight with a reflector and clear lens.
I choose different LEDs depending on the CCT I want. I think the <4000k E21a is a better option than 219b or 219c. My priority is not to have tint above the BBL, at any power level.
I avoid flip chips like the plague, due to tint shift across the beam, in a reflector
imo flip chips should only be used w pebbled TiR, a lee filter wont fix an inconsistent tint across the beam, diffusion film wont either.
I do like having a Lee filter option, but it did not help my Olight S1 w High CRI XP-G3 flip chip. It made the hotspot way too pink when it was strong enough to kill the green in the spill. That light uses a frosted TiR, fail. Even when a flip chip tests below the BBL, as HDS reports for their XP-G3 offering, that does not mean there is no green in the spill. They dont test tint across the beam, only the average tint of the entire output.
I respect Geuzzz opinion that the SST-20 may be useful below 4000, no experience
I agree with LightBringers opinion that the N219b is consistent across the beam at any given brightness, unlike a flip chip, that is NEVER consistent across the beam, at ANY brightness. And I respect his opinion that the LH351D may be worthy of consideration. I also agree that the 219c tint, above the BBL does not work for my spoiled self, as well as my sw45k.
I have another flashoholic friend making similar recommendation of the LH351D, specifically for a 5000k dedome, making it “almost” like a Nichia. The LH351D is brighter, but that is not a priority for my use, which is mainly close range, indoors, and less than 200 lumens. That friend is presently choosing to carry an sw45k single in a reflector with clear lens. No Lee filter, no diffusion, just pure pink goodness.
maukka has shown that tint shift across power levels does not produce tint above the BBL with the sw45k. That is also my experience, no green, no matter how low I go, and I often use less than 20 lumens.
To make a decision on which LED to use, it depends on priority ranking of several criteria.
max lumens does not favor N219b, that is its weakness in a marketplace that emphasizes lumens over CRI, at the expense of Tint above the BBL.
choice of battery size impacts expectations of max lumens, I dont use 18650, nor turbo, on my lights.
my preference for small lights comes with a preference for small lumen levels (low power levels), which is a good match for my choice of sw45k. I see no reason to change that atm, given my current use patterns and preferences.