I have always tended to go with more 250W-400W Mh and Hps, just because of heat factors, even though I have air cooled lampholders, I think that the distribuition is more equally spread out instead of just one or two central lights... I currently use one 400W MH and three 250W HPS in a 2'X4' closet, with 8 five gallon buckets sittin just over a drain pan, and it always turns out sum awesum sugar-coated, sweet-smellin' donkey dicks... Keeps from having to rotate my containers so much also, because they tend to stretch less towards any one particular lamp... And, with the mixed spectrums, timed just as in nature starting with my hps's and cfl's, then three or four hours after they wake up to that, the mh comes on, until about 3 or 4 hours before they go to sleep, especially during veg phase, I have noticed so many subtle and very noticable differences in their growth patterns and I am sold forever on duel spec lighting... Always have been anyways since I wire so many for a living as an industrial journeyman electrician...