I was wondering that too. I haven’t seen any comparisons anywhere.
If we look at one led the XP-G2 only can draw around 4,5A or a little more with a DD fet driver due to higher forward voltage. At this current it puts out 1000-1100 lumens. But an XP-L or HI version can draw about 6A because lower forward voltage. And those leds put out 1500-1700 lumens so an XP-L has more output but higher current and more heat and faster draining battery.
The XP-G2 is being overdriven by a larger margin, makes more heat… like the Nichia 219C. The XP-L is rated for 3A, so we’re really not pushing it that much over it’s safe limits and as such, don’t see the heat problem. The smaller dies of the XP-G2 and Nichia give us more throw, the lower lumens of the XP-G2 are not as desirable.
In a triple or quad, the XP-L HI or HD is not likely to be pulling full direct drive power, typically only around 15A max in a triple so only about 5A per emitter, if that. The XP-G2 is not rated for 3A, merely 1.5A, so it’s getting overdriven a lot more. Cree states that the “high efficacy” variant can do 2A and has a Vf of around 3.08V at that level, while the standard is rated at 1.5A and Vf is about 3.13V. So, it’s only when pushed really hard that the XP-G2 shows a limiting forward voltage. These can be pushed to around 5.5A with a Buck driver for some 1100 lumens, lot of heat to deal with of course.
Edit: FWIW, their high efficacy variant is a flip chip with phosphor out to the edges where the standard model shows bond wires and the silvery substrate. 
Edit II: The high efficacy model is only rated to do 765 lumens at 2A.
Thank you both for your responses,I really appreciate them. I am going to wait for Mtn elect to just get xp-l hi back in stock.
In general, XP-L HI works better… but it also costs more.
It’s brighter, throwier, and has less tint shift. But that may or may not be worth the extra cost. XP-G2 is still very nice at lower levels.
Agreed, the XP-G2 S4 3D is very nice. I have 4 that I removed from my D4S that I will find a home for, sometime or another…
I got mine with XP-L emitters yesterday and I absolutely love it. Very nice light! The magnetic cap and lanyard hole are nice additions. The tritium sticks are a cool feature as well. Heat dissipation and step-down from max are much improved over the original D4. Side by side comparison with my original D4 show the S model out-throws it my about 50% and output is noticeably brighter. I highly recommend this light.
Thanks Toykeeper I really appreciate you taking the time to respond and also working on this flashlight.
Finally pulled the trigger and got a XP-L HI 3a in gray on the way!! I am beyond excited, I think I am more excited for this light than I was my Imalent DX80. After using the Q8 wonderful UI all other flashlights just feel very cheap even the DX80.
Ya…this UI really takes it to a magic level beyond “low-med-high”…hard to even consider lights that don’t have it…
Glad to hear all these nice comments about the budget emitters. Just ordered an Xp-g version cuz I just couldn’t swing the extra money, and believe it or not, I won’t be using much of the max output anyway. I’ve got the max set for about 300 lumens on my D4 and am happy with it. May set this one to around 500. The longer runtime is one of the appeals of this light for me, and of course the UI and compact design.
Ther ar no tritiums in the D4S.
Those are leds.
Did you retest yours after you calibrated it with the Maukka lights? If you’re getting about 5k lumens with your v3 flux bin, then I think something is wrong with my v2 flux bin only getting 3.8k lumens.
Edit: nvm, I just read your retest, which is more inline with what I would expect. BTW, I will retest the ROT66s with a heat gun to see why one steps down so much faster than the other.
Finally my D4S arrived to me.
(It’s been in Sweden since Aug 12, but the Swedish PostNord is not what it used to be. Handling paying for sales tax (new) took it’s time and the fee charged horrendous. With DHL it only takes ONE day and costs way less in adm. charge.)
Anyway, it was worth the wait, LOVE the light.
Looks great!
Neals deals D4S with “blue” aux on the right and Hanks aux on the left. look like the same to me! lol
maybe soon hank will offer different colours 
doesn’t seem to add the images
Cyan leds I found have extreme spectrum shift between low and high current. These aux leds, even on high setting, run well under the nominal current and so are more towards green than you expect from cyan leds.
Yes I’d consider them emerald LEDs for their usage in the D4s.
Thanks Alex64. What did I do wrong?
I did send an email telling Neal that they are more green to my eyes than the blue advertised. I was expecting the blue colour like you would in the trits. But I didn’t mind too much as that one will be used for work
Bring on some blue or purple aux leds :sunglasses: