I pulled 3 ounces per plant (4 plants) on my first CFL attempt, that was using 15x40watts of the 2700's during bloom and 2x23 watt 6500s, I used 6x23 watt 6500's to veg. I was also using coco coir, perlite, and sphagnum. My lumens were I think either 28k or 32k with a 3" ceiling at all times. I promise you, I spent well over $150 on my CFL setup. I'm very proud of my CFL setup, however, switching to HPS was a better move, and the startup costs honestly weren't that much different. If your only planning on buying 3-4 decent CFL bulbs, expect that in your yields, more light = more bud.

If I were growing with 7000 lumens, I would celebrate at anything more than a 1/4. your not talking about ounces, your talking grams.... keep that in mind.

PLEASE NOTE: I'm not saying you can't grow with just a few bulbs, and I'm not saying you can't get a decent yield, you can on both counts, but you'd have to spread 3-4 bulbs (2700's) across an almost flat box, and LST your plant to be flat, that way you can maximize the amount of light it gets across the entire thing. You can do ALOT with minimal lighting, but experience plays more of a factor in those cases than lighting. I can veg 6 plants successfully (and quickly) on 3 23 watt bulbs using DWC... but my skillset has focused on continuing my education in not only cannabis cultivation, but cultivation of all plants, lighting techniques, and FIM/LST methods.

So for any of us to say "no, you can't get an ounce off 7000 lumens" is incorrect - Can you? Yes. But its not likely.