T5 tubes are great and u get nice results, but u wont get near a 400w HPS unless u use shit loads of them tubes...i use an HPS for flower and she puts out 52 000 lummens so it means u would need 10 of those T5´s.Anyway for small spaces tubes are allways a smart choice and they´re cheap and take less juice the HID´s so all things considered they´re a good choice.