I have not yet grown with cobs, but I've grown with just about everything else. My LED panel works fine, HID lights are inefficient as hell but make up for it if you go vertical (600w+ will grow the shit out of a small to medium grow room, just keep it from getting too hot), and you will get results from either. I don't see CFL as useful for much more than being a complementary light source for other more powerful and efficient lights. I'm getting parts together now to build a 200w cob, and while I'm a huge fan of cross lighting with all different types of light, ultimately I would like to go mostly, if not all cob with my setup in the future. People seem to get the best results with the lowest amount of watts with cob.