Exactly, 1000W MH > 400W HPS any day. The more light output trumps the color spectrum.
If you really concerned about using MH and not HPS to flower why not spend the $200 for the hortilux ultra ace 940w HPS conversion bulb to run HPS on your MH ballast? Thats what I will be doing in soon as I can afford it, right now I'm just using my 1000W MH and am very happy with the results. I just got it for $100 a few weeks ago and moved my 400W switchable ballast/bulb/hood into my veg room and am running the 1000W MH in the flower room.