I've tried getting the 90 watt UFO light, but it was very noisy with it's fan and eventually half the leds burnt out within a few days so I had to return it. I did find that the vegetative growth during that time on my plants seemed pretty solid especially for comparatively weak light. If you do get one, I would suggest going with the generation v type
Blue Red 225 SMD LED Grow Light Panel 30w Indoor Garden Hydroponic Plant Lamp | eBay
It would suck to have a fan burn out or the lights stop working all of a sudden due to overheating, but from a week of using leds, I believe that a 90 watt led is by far more useful than a 70watt consuming cfl. Of course it's performance may be inferior to that of a true 400 watt metal halide, hps or any other commercial greenhouse light but I believe leds are pretty useful as long as you don't get the 9 watt consuming cheap stuff which is hardly sufficient for a night light.