No, you have that the wrong way around. FET+PWM (or in DC FET= “Turbo”) is the least efficient way of driving an LED. But can give spectacular output when over-driving LEDs. Irrelevant for a lantern, actually undesirable.
Look at all the chatter about which FET, cell, LED, host, reflector, MCPCB, copper addition, spring mods. etc. can, in combination, give “Max Power”—-) for a few seconds before they overheat. Really not relevant for a lantern IMHO.
FET+1, the staple BLF driver architecture, uses 7135 linear up to 350 mA, then the FET kicks in (inefficiently) above that. The single 7135 also allows the efficient firefly and moonlight modes that would not be possible with just a crude FET. And would have some utility in a lantern.
Linear drive, typically using a bunch of 7135s, either banked up in sophisticated manner like Mike C does, or double-down or triple-down, or just one bank sized for max. output, with fast PWM to dim down, is a decent compromise of efficiency, cost, complexity, ease of design.
Personally I wish the 7135 had never been invented. It has stifled innovation for so many years because it works and scales so well, and is inexpensive. Due to being cloned (sometimes well, sometimes not) by so many others (I don’t even think AMC exists any more).
What Led4Power is doing is much more clever, but proprietary. And I fully agree it should be proprietary, speaking as a professional electronics engineer who has to make a living.
This has always been the case for BLF hardware, there is a great reluctance to actually publish schematic diagrams and bills of material for review and critique, I have mostly had to reverse-engineer them from e.g. the OSHpark layouts.
I see that this is also the way that some BLF designers are now working, in some sort of collaboration with manufacturers. Be it hardware or firmware. And I support that. OSHpark and the various open source software models are fine, but not something that I particularly embrace. Engineers should be paid for their efforts by commercial manufacturers, no matter how derivative they are.
If they choose to give away their unique innovations, circuit design, algorithms, hard-won empirical knowledge, that’s down to them (I would not). If they simply re-purpose derivative works from others, that’s down to their conscience as to whether they also acknowledge their inspiration.
Decent work should be rewarded. Whether financially, or by seeking popular acclamation, or the worthiness of “charity”, or otherwise.
Motivation is a complicated subject, particularly on social media like this, we are all different, there are no simple truths.