I think you are looking at this is reverse. Rather than thinking of the right amount of plants per light, you would be better served determining the proper lumen's per square foot and go on to determine how many plants you want per sq ft.
Start with lumen's and work toward the proper number of plants.
In my opinion, the answer to your question is no. The main cola on the plant will produce the best buds and that is what you should really be focusing on. The buds from the lower branches are not as good. So the increase in yield from light hitting the lower portion isnt going to make that much of a difference. If you think your area is cramped, adjust by pruning. I think more agressive pruning would help to increase your yield as opposed to reducing the number of plants.
Thats a very good post!!
I too am expirementing with numbers vs size. I think it all adds up to the math in the cycles. If you want a short veg and flip quickly, I'd say you can go for about 20 gals under the 1000w in a 3.5x3.5. Maybe a 2-3 week veg cycle.
If you want longer veg times, you'd half that ammount of plants. I think you should focus on the ammount of canopy and overall height, rather than the numbers. Theres so many factors. I grew 6 bigbang under the same cycle as 6blueberry. I had to break over the blue a ton of times, and theres no crowding. The big bang stayed at 22" tall when flipped at 10", and are crowding like hell. So, the evidence is suggesting that a given number of plants is impossible to say. More likely, you should go with what youve got, and tweak from there.
As far as yield, About 20-35% of my last yield was those little baby nugs, under the first canopy layer. Granted they werent the best, they still didnt get any complaints, and it was 30%! If you are looking for yield in total, Id say to cram em in like you got em, prune them a tad, and keep air blowing. I actually harvest the top nugs, continue flush for a week, and go back to the baby nugs. I dont gain yield, but they do darken and ripen. Nowadays I prefer quality over yield, so im limiting it to about 12 gals under a 1000, flipped at the 4th-5th leafset 10-12 inches. I quit topping the plants because I lost the MEGA colas, and seemed to lose a tad of those yielding baby nugs.
So many varibles is what makes this fun imo. Sorry I cant tell you a definate answer. I beleive the answer lies in perfecting a certain setup, with a certain breed, under certain pruning/handling conditions. Consider it a personal challenge that only you can win! Good luck to ya