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@gbj_tester
Hard to say. At first I was surprised that somebody stuck 6 x XP-G R5 emitters in a box and only claimed 1700lm, because the usual marketing BS requires people to use the highest possible drive current and advertise the gross lamp lumens at that, which would be ~2800lm @ 1500mA for that emitter bundle. So, by way of example, I "did the math", which anybody with the Cree datasheets to hand can do, and discovered the claimed combination of output x duration was pushing the bounds of credibility. I'm not up on the current state of driver circuit design, so maybe >90% is achievable, but that does mean that you have to sacrifice beam shaping for utilisation factor (lumens coming out of the lamp housing/bare chip lumens) in order to get the claimed lab measurement, which could be a false economy. I'd rather have an optical system which put 50% of the lamp output exactly where I want it rather than an omnidirectional pattern, since the useful part of a uniform hemispherical output is about 1/2π or 16% for a conical beam with a spread of 65°
The lesson is to take all marketing numbers with a huge pinch of salt. The important measure is how much light falls on the bit of scenery you need to avoid crashing into, and that's a combination of lamp output, thermal design (lamp lumens drop off fast as the junction temperature goes up, so better cooling can make a material difference) and optical design (how the combination of reflectors and lenses directs the omnidirectional lamp output towards where the light is needed)
Runtime is better with many emitters on low settings than a few emitters on high settings, because LEDs are less efficient at high currents, e.g. for XP-G R5
139lm/350mA*3.00V=132lm/W
463lm/1500mA*3.5V=88lm/W
but adding more emitters makes lights expensive and large, so they don't bother to tell you this. For any given emitter & battery, you get about 50% more run time at the same total output by using 3-4 times as many LEDs at ⅓ to ¼ of the current. Using a lower current also makes it easier to keep the junction temperature down, further improving efficiency, as output drops by about 0.25% per degree above 25°C. With lamps being small and light and batteries big and heavy, it may be better (per my earlier post) to add lamp heads rather than increasing the battery size to achieve the desired result.