First, it's "guerilla".
Now, to be of help, you really have to be pulling better than one per light before you start thinking about expanding. You need to figure out why you aren't pulling better numbers with your current setup. You might want to consider hydro, but I know that some of the soil guys here on RIU crush it, so if that is what you're comfortable with, than stay with it. You might want to look into the "super soil" threads(is it super soil? build a soil? soil guys, help me out here) if you're just running store bought soil.
My suggestions for upgrading your current setup -----> Consider purchasing 4 315s. Sell 2 of your 1Ks. Put the 315s in the corners, with the remaining 1K in the middle. You'l probably pul the same numbers, while using less heat and elec. Get remote ballast 315s. Or, replace your 3 1Ks with 3 750 DEs. Or go LED, but the initial light purchase will be substantially more than my first 2 suggestions.
Last, LEDs don't use half the power consumption. With current tech, you need about 75% of the watts you would need for an DID setup, meaning it takes 650 to 800 watts of LED to replace a 1K. They still generate heat, but you can run less watts, which equates to less heat.
Oh, and stop referring to yourself as a commercial grower. That term tends to apply to licensed growers. You're just a grower, dude.