Absolutely Stinky. As a matter of fact I used my MH's for the first 10 days of 12/12 this last cycle and it did reduce stretch. I also received a dual arc light from my local hydro shop to try next time. It's 600watts hps and 400 mh. While I'm looking forward to evaluating it I don't really expect it to make a difference, except maybe reducing stretch. But if it does I'll let you know.