Thanks for the replies.
If I could, I would use both HPS and MH.
But as my flower-space has only one HPS bulb, which need replacing, I figured the extra blue would not hurt.
They love the extra spectrum in flowering.
But then again, it's not "extra blue", it is the same watts so the output must has less red, correct?
I'm really on the fence on this issue, wish somebody else had any input as I got conflicting advise by previous posters.
Edit: Anyone else? (got conflicting responses)