round my way a 600 would cost around the same as a 400,i would go for a single 600 on its own in that space,with a 25% reduction in electric and less hassle with air cooling 2 lights, same amount of hempys either way!
my pal swim would run 7 hempys one way multiplied by 12 hempys the other which gives you the option to discard a few of the wimps, or reduce to whatever number if they become over crowded, swim has found that they will all find their own way if you leave them without doing any more than small adjustments to the hempys,swim finds it helpfull to cut a few lower branches off after a week of flower
to get a nice air flow and even canopy, swim also likes to set 10% extra plants away than needed to cull the worst 10% when they get trimmed ,he waits sometimes longer than a week to do this so he can see which brances to clip and which girls to remove also he's a lazy fucker! he aint noticed much shock time if any with these little hempys , but he does note that when he cant be arsed pruning them at the right time and he lets them go un-cut they get constricted and the lower buds suffer anyway and of course the main colas aren't as big.
