Hey mole, great little units!! I used to own 2 of em. did a years worth of growing with them, then switched to LED. The only problem is they aren't ducted, and for a small space, they will put off a fair amount of heat. They are heavy for what they are, but the balast is built in. I would go for the 400w cool tube, and duct it with a speed bully. In terms of yield and bud size and growth, the 400 would be the way to go IMO. Just be sure that when you go to purchase, you really think about resale if you find you dont like it, or want more wattage in the grow space. Todays good deal is mot likely tomorrows garage sale. FYI they also make a 400w unit like the 250w, But again they are not ducted.