I already have a 1000w hps set up,a 400w hps set up and a 400w mh set up.
I find the plants like both lights[400w mh & 400w hps] during veg growth.
Before i made another room i used the 1000w hps and 400w hps for flowering and vegging.Now i use the 2 400w lights for vegging.More light spread out over the 6ftx3ft chamber.
The flowering room is 5ftx6ft,i plan on adding another 400w to it.I get great results with that much light in that chamber.