I have a 200 watt vero at about 120 watts in a tent growing 1 king tut (Sativa dominant)
I have 3 sativa dominat in a tent (trainwreck/jack herer)
It is not scientific but wow that king tut is thick in the stalk. And so tight for internodal distance i keep looking for errors. But water is good ph is good tds is good. I grew that king tut in my tent before and it was scrawny in the stem.
I personally am going to sell all of my lights and get a timber fixture to fit in the tent. 400 watts or 600 watts vero cobs because i really love that light. I love the 315 as well. But it is not as dense of plant. I could grow a monster with veros. Well 4 of them exactly
I am always contending with optimal heat. 315w to 400w is about he max where i have my tent so whatever gets that done the best is my goal. I have not tried quantum boards but from everything I have tried I love real cobs. Vero cobs. Best damned light I have ever seen and I have tried mars/mcob/cmh/
CMH is the best of those but 315 watts is good 400 watts is enough better.