Thx for putting this up on the forum. Let's put that issue to bed. I asked HLG this specific question last year. 'Does dimming my lamp change the spectrum? I was told, "no, not enough to matter in agriculture". IDK if that is specific to HLG or not. But, I have adopted the mindset that dimming the light only affects intensity, not the light spectrum. My last auto grow the light never got above 5 clicks of 10 on the dial. Had the best harvest of my somewhat short auto grow experience. Because I harvested 8oz from one plant, I'm now convinced I can turn down the intensity w/o fear of limited or reduced yields.
I'm growing 4 sativa's that are vegging under the HLG Scorpion Rspec. The light is about 30" above the canopy at 2 clicks on the 10 click dial. Plants have tight node spacing, no light burns, no burnt tips, no heat issues. I'm using a Phantom PhotoBio light meter (recommended by someone on the forum) to measure umols. At that setting my plants are getting the right light in the recommended range for their stage of growth.