This green supplemented spectrum is based around an article/study about green light being more efficiently photosynthetically at high intensities than red light, apparently due to penetrating deeper into the leaf and cannopy. This study is only really publicly available as an abstract, never been able to read the whole study or see the numbers. To my knowledge this is the only mention of this online. Yes, it could be marketing hype but i do think mammoth probably tested their new spectrum with at least some positive results, likely somewhat better yield.
However im not completely sold on green. From general horticulture (but i havent really seen any canna related science): green has a morphological response in the plant based around where it is most prominent: intra cannopy, where green is very abundant.
The plant green response is based around reversing the blue response (transpiration, node length etc) but it also changes the type of plant tissue grown; green grows a more fibrous tissue of more of a support character; like if the plant was trying to build more branch like tissue with more fibrous growth. This makes sense; if high green is the "intracannopy" trigger we could expect it create ideal plant conditions in an intracannopy environment; low transpiration means the water and nutes get redirected towards top cannopy and apical growth while also creating tissue which will better support the top cannopy; branches and fibrous growth.
Being more fibrous its very possible that green yields very well but i dont think that extra yield really adds more than just weight by making bud growth of more dense and fibrous tissue. Dense, as in buds weighing more for the same size. More weight but same, or even slightly diluted high. Our own tests of various different white diodes and monos hasnt really given any positive results in quality with regards to green. However i dont have any real numbers to support this, only that our green heavy fixture (4000k +660 + uva/uvb + far red) was underwhelming when it came to our subjective evaluation of quality and other green heavy fixtures following the same trend.
Ive attached a screenshot of me googling this green study; look for the irony below:
View attachment 5379075
Google answers other popular querries regarding green and seems be answering why green is minimally effective in photosynthesis but in the next breath why its the most efficient color in photosynthesis. So there really doesnt seem to be much consensus.