I have tested both the HK04 (4x XHP50.2) and the Sofirn Q8 Pro (4x XHP50.2)

I use high-drain batteries to test (for the Q8 Pro, I did not use the Sofirn 3000mAh 18650 batteries which are not as powerful as higher-drain type 18650 batteries).

The Sofirn Q8 Pro is brighter compared to the HK04.
(I don’t have a light integration device for measuring lumens but just doing the same ceiling bounce and taking a lux reading, my Q8 Pro register 1400+ lux on Turbo mode (at turn On) whereas the HK04 gets only around 1100 lux (at turn On)

Thus the Q8 Pro is brighter in actual than the HK04 — I think the main reason is having 3 batteries just cannot power 4x XHP50.2 to the max levels, compared to having 4 batteries.

Haikelite HK04 (4x XHP50.2) beamshot

Sofirn Q8 Pro (4x XHP50.2) beamshot

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At closer distance, it’s a bit difficult to compare brightness since both are very bright (the Q8 Pro having a bit wider area of light)
Haikelite HK04 XHP50.2 (left side) vs Sofirn Q8 Pro (right side)