HPS can be used effectively for the whole grow IF you have a bulb with an expanded blue spectrum to enhance veg growth. They don't make 150 watt bulbs like that, only 400 watt and above. Otherwise you need a MH for veg and a HPS for flowering. I doubt that fixture will run an MH bulb, so you would need a conversion bulb. To my knowledge, conversion bulbs are only made for 400 watt and above. Get the Bad Boy. The increased yield will more than pay for any price difference.