Lumens mean a lot, but that's not the only factor. The reason HPS lights are so much better than CFLs (at least for flowering) is because the color of the light is much different (around 5000 kelvins for the CFL; and 2100 for the HPS). There's also the issue of price; you could get almost 10 hps bulbs for the price of 2-200watt CFLs - minus the cost of the ballast of course. Also, if you decide to go with the CFLs, I would place them in a horizontal position because a lot more light would be getting to the plants.

Just one more thing - I would line the inside of the cabinet with mylar or paint it white; that would eliminate you having to rotate the plants for even lighting.

happy growing.