In a 4x4 i would run 2 315s. Eliminates the need for spectrum supplement, comparable to a 1,000w se hps, twice the bulbe life, a phillips master color is cheaper than a 6 or thowy eye hortilux, better overall quality (colors, terps, potentcy). It will be sooner than you think that old school hid lighting will be long gone and cmh will be the entry level lighting, unless leds come down in price. I got a sun spectra 630 setup with bulbs, ballast and 2 reflectors for $500 to my door. It usually comes with 1 duel bulb hood for the 630 setup but i like the idea of running it as 2 315s. Watt for watt they will destroy se hps, its very close to de though de does out perform. On the flip side of that, cmh is easier to deal with i regards to height above canopy. They do put out a good deal of uv though so you should run them higher than an hps. Ive run hps for years. I now run cob led and cmh and will never look back. True full spectrum white light is the way to go if youre not using the sun. The initial cost is the only thing hps has going for it but the long term savings and gains of cmh vs. hps will make up for it many times over. Fwiw. Just trying to help. This is an idustry/hobby filled with snake oil, smoke & mirrors. Do what you will. Not my grow, not my money.