i have had a buddy test 600 for a grow,he recorded the light output useing a light meter photoraphers use,there was no increase in light,with the digis,he was not ready to justify spending 400 dollars a piece to upgrade to them which is the price in western canada,but he found his hydro bill only had a 5%change from the magnetics,but yes less heat,but he has them in a seperate room,and they probably do increase lamp life,but they did not increase his yield,that remained the same for that time of year as every other time for last four years.