I can tell you that those lights will be fine, as I have a 200 watt CFL, and you probably already know this, but those puppies put off a lot of heat, so make sure the space right under the light and above the plants doesn't get too hot. Make sure you're using refelectors properly. I belive that you can have quite a lot of plants in there, as long as you flower early, and I think that your yield won't increase but you will be able to harvest in half the time, like you are thinking, but make sure that you get a strain that finishes quickly and can handle SOG well.