Have you tried with and without spreaders?
Nope, but I intend too. You can supposedly get an adjustawing inches from the canopy with the spreader. Ill be able to see for myself, and see what I prefer pretty soon.
It makes sense to me that the spreader makes for a more even distribution of light and heat across the length of the reflector, which means it can go lower or the plants can be grown with less room height. Yes it may reduce lumens directly under the bulb, but gives back across the entire canopy as the plants get different angles of reflection from the bulb penetrating different areas.
Light from one direction casts shadow right? so light bouncing off the spreader back onto the reflector changes the angle of light, meaning there is more usable penetration into the canopy like a prism effect.
The spreader is so close to the bulb and reflects 97% of light meaning the spreader itself almost becomes like another bulb offering light in way more directions. In the same way that a light mover takes intensity away from one area and gives light to other areas (obviously a light mover is more effecient at this).
Like if in a game of snooker you were not allowed to bounce balls off the cushion, youd be potting less balls right ?