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Lezyne Micro Drive 600XL front light.
Claimed output: 600 lumens
Measured output: 681 lumens
And the good news is that after 5 minutes in the integrating sphere, output was still 622 lumens showing excellent heat management for such a small light.
First thing I noticed was how much brighter it is than the Macro 600XL that I tested a couple of years back. With such a small light, the battery is obviously also very small and I couldn't get more than 55 minutes on the highest mode. So very much a commuter light, but a pretty good one if you don't mind frequent charging.
At around £45, I would prefer the Bikehut 1000. A bit bigger, but brighter, cheaper and a longer run time.
I have an 800 XL from a few years ago. Nice unit, but the beam pattern was far too floody resulting in having to use a higher power than I otherwise would have meaning the battery life in practical terms was no better. A lot of lumens, but most of them are wasted.