Do you find the UVB light to be that beneficial? Have you done several runs with and without for a comparison? I've read the U of MD study from long ago, I know some people swear by the Cmh's and other's cobs, I've read a ton of threads and heard the hype vs others saying meh, etc, etc.
I won't be moving away from my DE HPS, but I am considering supplementing with a row of CMH with 4100k bulbs down the middle. Sure, the spectrum will definitely make it better, but worth the expense and electricity (heat and light)... hmmm. ??