From what I know it would actually be better. It would have more coverage than 1 bulb and light hitting the plants from more than 1 angle. But hps is just for flowering...
HPS is not just for flowering, it can be used for both vegetative growth and flowering, though a MH would be ideal for veg. I am currently on my second grow and we have had great results with our 400w hps.
thanks guys i'm glad you said that its the cheeper option to lol .im gonna try my hand at lowriders easy rider looks good to me . gonna put them in 2 gallon pots not sure what food to give them is dynamite any good .