We tested the m135 at 275 watt on a radium and from the guy who tested
(a lighting engener) he said this ballast underdrive the bulb and it will shorter the bulb life
he also tested the 400 wath sodium and said this ballast is the best ballast you could buy fot that bulb he also said the Agro will be harder on the bulb but how much we dont know but from my part I dont care I will keep my agro and keep the beautifull color
keep in mind that this bulb is not a 400 watt but a 360 watt energie saver
bulb
Here is a guy who have radium setup on agro for about 3 years and change is bulb at 12 month
http://trailertrash.homestead.com/lights.html