What are you using to flower? Are you planning on using the combination lights for the entire process? What I know is that the MH blue spectrum is best for creating small internode spacing and this is what is desireable I assume. The only reson I think it would be better than 800 watts MH is saving dough on a new light fixture. If space isn't an issue then it seems like the thing to do...HIDs, burn em' if you got em'

Jay