could be correct, until battery voltage meets led Vf linear drivers are terribly inefficient, if you looking for efficiany, you need the driver to be efficient at entire voltage range, battery cuts off at 2,7v, so linears are only very efficient between 3 and 2,7v range, from 4,2v to 3v they burn energy away, especially when we are talking low current, (200-400lm) , it will take a while for the cell to drain to 3v,
i do not think sofirns and convoys use boost-buck, when it comes to 3v led and 1 cell lights, they use linear drivers,
yes fets are not regulated, they are basically direct drives, no regulation at all, except for some in low modes, that have linear regulation, fet +1 or +2, means 1 or 2 amc linear regulators, others just use pwm for dimming.
i’m not sure what beam pattern has to do with electrical efficiency, it has no effect on it, optical efficiency, yes. you can find that number in optic datasheet, no guesses needed,
as far as firmware, not sure . it may affect electrical efficiency in some ways, or it may not, maybe someone who designs drivers will come and comment on that