I have 2 of the older lights from several years ago. I just completed a single 5g fabric pot coco manifold with 8 mains, GH trio, Panamagoo fem freebie from Mass Medical. The clone I used was from a seed mother I had just flowered, so this was my second run with this exact genetic and my third run overall with Panamagoo since I'd grown 2 other seeds previously through harvest.
I kept the two cobs about 10 inches apart, measured from the hanging loop at the top of the driver. The plants were vegged until each of the 8 mains on the manifold grew 4 nodes vertically. The lights were 18" from the tops at beginning of flower, ending at about 12" by harvest. I use angelina reflectors. Night temps were 65-68F, lights on 70-78 depending on proximity to lights.
Total dry weight after trim was 75g. If I had deleafed this plant around day 21, I imagine I could have added another 10-12g to that number, but I'm experiencing low RH at the moment and deleafing when it's dry seems to throw my plants into a tailspin, so I avoid this technique until the spring.
My only gripe with cobs versus a QB is light spread. The buds right under the cobs are the best I've ever seen, but you really need a flat flat plant to get much from the lower or sides of the plant. My space also demands a smaller plant overall, so I think I overshot my container volume and grew too much plant for my tent, keeping some of the colas pushed against the walls.
D. You should not be considering anything under 1.8 PPFD in 2020. 
