Best 17mm driver board for minimag conversion

Im trying to source parts for a mini mag conversion similar to match's minimag mod.
I want to use 2x 14500 cells and ideally use a 3 mode driver.
Im looking at using a cree XHP50 LED and running it at 1500mA for mode 1 which would give about 1200 lumens, I would like to have mode 2 around half of that at 600 lumens and mode 3 on low at around 200 lumens.

Question is, I would prefer a buck driver, due to more efficiency, but is there any significant advantage?

Reason im asking, is because there are so few buck drivers out there that are 17mm diameter, the MTN-MAXlp HP on mountain electronics looks a good choice, but unfortunatley it has components on the underside of the board, which affects my design. I want one with a flat base that can screw down on the flashlight body and make contact to turn on.

This one here looks a good alternative, but is not a buck converter. Likely it will have a zener diode installed.
https://asflashlights.com/-diy-part...tml#/69-optional_parts-none/68-voltage-6_volt

I also see there are liner regulated boards available, so these will simply convert excess voltage into heat when regulating, so not very efficient, not to mention more heat generated.

Any other suggestions out there? Ive seen plenty of single mode drivers out there, but thats not much help.

Could I go with a 3V LED instead? Ive been trying to find 3V options, but the 3V LED's im looking at are not as efficient as the 6V XHP50.

TIA

have a look at the SSt-20 performance at high current

MtnElectronics also has a zener mod 17mm driver that I've used with 2x lithium cells. It's for a 6v LED, if that makes any difference to you.
search for
[h=1]QLITE 6V+ Zener Mod - For 6V MT-G2/XHP[/h]

DrafterDan said:

MtnElectronics also has a zener mod 17mm driver that I've used with 2x lithium cells. It's for a 6v LED, if that makes any difference to you.
search for
QLITE 6V+ Zener Mod - For 6V MT-G2/XHP

Click to expand...

Yes, ive been looking at their driver, my main concern is that all these drivers are basically linear voltage regulators, and would have significant losses compared to a buck driver.
Are there any other options out there with a buck driver 17mm or smaller?

I believe I've read that small buck drivers are rare to non-existent. MTN will probably have the best option(s). Also there is a 3V XHP50 now.

light-modder said:

I believe I've read that small buck drivers are rare to non-existent. MTN will probably have the best option(s). Also there is a 3V XHP50 now.

Click to expand...

Yes, i see that there is, would be perfect for AA use. I was wanting to use 2 14500 lithium cells to give a longer runtime, so thats part of my problem im facing.