This interview I found interesting, he notes a linear increase in yield with increasing pppfd up to and beyond 2000ppfd (so long as no limiting factors are present).. I thought bugbee had said peak efficiency was around 1500ppfd then tapered off rapidly..
And also that it’s not so much leaf surface temp in late flower that needs to be optimised so much as flower (bud) temperature. Perhaps I’ll get out the temp gun and play with AC hitting the canopy
I might also have to revisit my habit of dialing ppfd back toward the end of bloom.