The lowest mode that is available on all of my lights is ok/fine with me. I classify lights based on lumens specs based on upper end, not the lower end. The only time I use ultra low mode is to see what the emitter(s) look(s) like when it(they) are powered on. My smallest light that has a higher lowest mode is Imalent MS03, at 150 lumens. I have to admit that maybe a little lower than that could possibly be a little better.
Moon mode is nice to have, but rarely do I use it. The only time I do is when I’m away from home and I don’t want the bedroom totally dark all night. It’s amazing how your eyes will adjust to minuscule lumens enough to not bang into something on the way to the bathroom. And if I ever got stuck in a cave, the moon mode on 1 of my ZebraLights will last several months.
My wife goes to bed much earlier than me. I use ML every night to navigate my way into the bedroom. We don’t use any night lights anywhere. With all the trees around us plus closed shades it is usually darkish to very dark inside. Years ago I had better night vision, not so great anymore. A ML flashlight saves me from bashing a tow or someting and is dim enough that I won’t disturb anyone who is sleeping. ML is more than sufficient light for this.
I use a FW3A with the later version of Anduril in which if the light is set to use ramping and the light is electronically locked, a press-hold (1H) gives ML and a click, click & hold (2H) gives the low floor level that the non-ramped levels is set to. I find that ideal for night (ML) and daytime peering in cupboards (Low by 2H).
Use moon every nite.
D4 right next to me on the nite stand for a piss run in my large totally dark master bedroom/bathroom. Not wanting to turn on bright room lite that will just make it even harder to fall back asleep, my nichia d4 is my choice, its the perfect nite piss light imo… Not sure how many lumen my d4 has when grabbing the lite and holding in the button till it just lites up with a nice warm eye soothing real low moon glow, perfect for a tail stand candle on back of the toilet with no eye strain…
Got to love Narsil for predictability… as fiddling with tail button modes half asleep blinding yourself with mega lumen by mistake is troublesome for some of us…
d4 Moon is even a good nooky light, tail standing on the headboard reflecting off the mirror puts a nice low glow on….
jmo
When camping in groups, the old method for not blinding everyone was to hold your hand over the light and only let a little crack escape. So the only thing that has changed is that this can now be accomplished much more conveniently and efficiently. It was always a necessary feature, even before it was an option.
Using a light outdoors in an urban environment, low (about 10 Lumens) was my preferred lowest mode. But when my eyes are accustomed to black, that moon mode is a savior. Problem is some lights don’t behave the same, and I get a memorised last level ON w/ the long press. Ouch!
So yeah, Moon (or Firefly) as a separate setting from the main sequence. I prefer the long press to Moon with another long press to OFF.
I will echo others, the importance of moon mode depends on the light, and the purpose of the light. If it is an EDC size light, moon mod might be needed. I am not however picking up an MF04 to use moon mode, so if and when my ordered MF04 ever arrives the existence or lack of moon mode is unimportant. The same could be said for an Imalent MS18 were such a lumen monster ever to be in my hands. It is like reverse on a motorcycle, on a 750 Kawasaki, it was not needed. On my Goldwing, it was very necessary to have.
For a small edc it’s essential, I won’t buy one without firefly (sub-lumen). With dark adapted eyes anything above 1 lumen is too bright.
Key chain lights are an exception and UI depends on who and what it’s intended for.
The light on my nightstand is a Jetbeam RRT-01 so it starts as low as I could possibly want however I do appreciate sub-lumen on pocket lights.
Direct access to a decent moonlight, direct access to highest output. To me this is the essence of a good UI and a good flashlight. I can live without a moonlight on a thrower. The lack of direct access to high on something like a Ti3 is quite acceptable for what it is. A general purpose EDC light without a moonlight mode is just not a good enough light for me these days. The SC31B is an excellent light but I wouldn’t want it for an EDC light because of the lack of moonlight. Works fine as long as I have my Ti3 in my pocket for the moonlight but without that I wouldn’t have something I need as EDC.
I agree with what others have already stated, moonlight or firefly mode is a must have in a smaller EDC light but in throwers or hot rods it’s not needed for me. It’s especially helpful in the middle of the night for a bathroom trip, since I have yet to discover the fountain of youth.
It’s a big factor - mostly used in EDCs, but it’s nice in all lights. I use it more than I use SOS or other strobe modes.
what i want is not a bunch of ‘named levels’ like moon, low, turbo, etc
what i want is for the light to start at .1 to .5 lumens, and quickly go in steps that seem equal, or ramping, all the way to 1000+ lumens.
i think it is stupid to have 3 or 4 levels and name them, or assume that each one has a definite purpose
and they end up with stupid steps like 1, 23, 47, 121, 150, 253, and 1200 lumens
wle
Everyone has a different preference. And different eyes. And different ambient light. And different house sizes and layouts with different amounts of clutter. And different Scope of usage.
I typically find even 0.1 lumen too bright at night. I’m further concerned it will wake up my wife.
tip #46...
If you've bought her a lovely keychain light...
Do not discuss the size of her moon .
It’s important for one light to have it. I am always up later than the wife so, I use it to get to bed without waking her up. She has thin eyelids she says. I dunno, I ain’t buying it. 
Instant access to a low but not moon mode is a must have in my nightstand light. If I have to be up and out of bed very quickly, moon isn’t enough. I need a bit more reach to search the house but not too bright to blind me. I keep the inside of the house pitch black at night and we live pretty rural so dark, is dark. I can see out but nobody can see in without giving themselves away.
So a Zebralight SC52w is my sneaking to bed light and a Olight M18 Maverick with the Luxeon V2 sits on the nightstand. I don’t know what the low output with that emitter in that light is but it’s as perfect as I have found. 5 lumens was stock but not sure with the Luxeon.
Wish they still made a reasonable output dual switch light like that. Thing will run for what seems like forever on a MJ1 or similar, even at brighter levels.
It is a must-have feature for lights to use for camping or a nightstand light - I will compromise on most other features, especially max output, to get moon mode for these uses.
It is nice to have for the rest.
I’d bet the overwhelming majority of us would give up moon mode if we had to choose between that and avoiding visible PWM.
But in general we don’t have to choose, so bring on moon mode!
Depends on the light. On lights I use for hunting, I want 100% mode and thats’s it. On headlamps I really like instant access to sub-lumen modes to see why the hell my dog is barking in the middle of the night when we’re both sleeping in a shelter or tent 
I can forgive my Nitecore Tubes to have visible PWM at low mode. Better this than no low mode when I need it. But yes, there are better choices.
Thanks all for participating. This poll remains open forever of course, but it seems to have been useful already in convincing someone to rethink their UI.
I like moon as much as I like my searing bright turbo. But if it affects me then please remove it.
They’re great for small pocket lights but not on the lumen monsters of any 18650 lights I know of.
Avoid if they’re made for inspection or tactical imo.
What I don’t like is that it’s only useful for my peelight. I prefer to start with medium.
Most lights with moon and no memory always need me to click multiple times to medium… Going through moon when you want a tactical instant on light isn’t practical as tactical nowadays are searing bright and always start on max which is also why I do not like.
Pretty confusing for newbies as they always assume my light ran outta batteries when it is no memory start on moonlight
Medium start with no memory please. Just how I have it on my FW3A. Click to medium… If I need I’ll hold for moonlight or double tap for turbo. If not then stay medium please.
I’m the weirdo that loves it M-L-H