Is the 21700 format worth the move?

[orbital]

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It's not just runtime either.
Larger batteries have the ability to keep better amperage at higher output.

Imagine a storm at night, a tree or something smashes into your roof & you need to go outside top thoroughly assess the situation.
You want a light that'll do a couple thousand lumens for a while & not having to worry about dimming or a battery going out.
If there's some big house issue at night, I'm taking a 2x26650 light, so a 21700 light is the next best thing...

There's little downside with added runtime/battery strength in anything battery powered.

 

[yellow]

You must not have a Nitecore E4K. That light is the perfect size for getting a good grip and the large

Agreed, looks small (enough)

and I just noticed that it is 26650 host, that I dont like to use.

But the other "problem" is, that (for 15+ years now) I no longer use "ready made" Flashlights;
the ones that are getting obsolete as soon as the next better led gets released.
(exaggeration of course, but it is a bit like that)
18650 P60 host bodies ...

... so I do have to wait till Fivemega (or anyone else?) offers an P60 / 21700 host
(waiting for that quite for years now, does not seem likely, though)

 

[Hooked on Fenix]

Agreed, looks small (enough)

and I just noticed that it is 26650 host, that I dont like to use.

But the other "problem" is, that (for 15+ years now) I no longer use "ready made" Flashlights;
the ones that are getting obsolete as soon as the next better led gets released.
(exaggeration of course, but it is a bit like that)
18650 P60 host bodies ...

... so I do have to wait till Fivemega (or anyone else?) offers an P60 / 21700 host
(waiting for that quite for years now, does not seem likely, though)

Nitecore E4K takes 21700, not 26650. 4400 lumens is near the upper limit of what a 15 amp (max. discharge) rated protected 21700 can handle. Lights brighter tend to use unprotected cells which can handle higher currents but have to have a protection circuit built into the light. That means the batteries aren’t removable. I try to avoid expensive lights that don’t have replaceable batteries. P60 hosts suffer from problems with heat transfer that limit brightness or cook the l.e.d.. If you’re okay with the limits in brightness of a Malkoff drop-in, that’s fine, but if you are looking for the next best thing, drop-ins are becoming outdated.

 

[LEDphile]

... so I do have to wait till Fivemega (or anyone else?) offers an P60 / 21700 host
(waiting for that quite for years now, does not seem likely, though)

I believe Malkoff has such a host, although it's certainly intended for use with their light engines

 

[fulee9999]

... so I do have to wait till Fivemega (or anyone else?) offers an P60 / 21700 host
(waiting for that quite for years now, does not seem likely, though)

as LEDphile said, Gene has a 21700 solution, it's called the MD21700:

MD21700 Body and Switch – Malkoff Devices

This the Malkoff Devices MD21700 Body and Switch. The body is constructed of 6061 T6 Aluminum and is Hard Anodized Type III HA Black. It is fully O-Ringed for weather tightness. The removable tailcap utilizes a McClicky forward clicky switch with momentary function. This body is compatible...

malkoffdevices.com

you can just pop a standard Malkoff MDX head on it, and off you go, enjoy your subsantial runtime on your favorite drop-ins.

Also, Vinh ( SkyLumen ) had a limited ( 100 pieces ) run of a p60 host with 21700, it's called the SLN bulletproof, it's a beast of a host, but a bit finnicky with drop-ins ( they went for around $250 without a drop-in )

 

[jumpstat]

Coincidently, I have a 21700 light from Wurkkos arriving soon. Its the TS22. I was impressed with how far these budget brands have come and I was really happy when I got the 18650 Wurkkos HD15 and FC12. Their workmanship is quite outstanding compred to those 3x their price range. One does not really need a separate charger as the workkus lights do have onboard charging ports, and they can be made to become power banks too if need be.