I'm in the process of expanding my room and was looking into buying 20 or so lights. I can get a fantastic deal on 400w psmh which i've used before with great success. Normaly i would go with 1000w or 600w hps depending on availability but because of this deal it would cost me atleast 6x the price. Will it really make a big difference. additinal info ceiling 8ft i grow em like trees befor flowering soil 25 or so diff strains veg under t8 cfl and psmh if you got other questions don't hesitate to ask
is that 14 x 20 ft? in an 8ft tall room? and your 400w setups are 6x less than the larger 600 or 1000? sorry to seem like some sort of bird but im trying to grasp your situation. if your room is that big, i would say you need to weigh the costs of lights to the results of said lights in your chosen growing fashion. since youre growing trees i can only imagine that larger lights would be easiest and best suited to penetrate into the canopy and fill out those trees. if in fact you are using a large space and multiple lighting units (i can only assume in such a large area) and youre going to take advantage of the 8ft of height as well you might want to consider throwing in vertical lighting with the 400 watters to get better penetration. i suppose most of this is happenstance and assumptions but i hope it helps you out.
Instead of spending money on lights and electric why not look into buying a light mover and have the current lights move across the room on a track, that way the lights can cover a larger space and with its movement also possibly cover shaded areas that was not getting light. Just an idea for you to consider