If it were me, I would go with 4x 600w cool tube design with a large reflector Each pair hooked up to a 750cfm carbon filter and 440cfm fan exhausting through the lights then outside. You are going to need a scrubber anyway, so why not run it through the lights. With tents, it's all about air flow, imo. With proper air flow, you can keep the temp inside the tent within 1-3 degrees of the temp outside the tent. I'm a big fan of LED's and COB's, but personally, I don't see anything wrong with HID's and they are cheap, cheap to replace and proven effective. Lots of other expenses too like fans, filters, medium, etc. I guess it all really depends on what your budget is. Good luck to you!