So lets see here. If you started with 600 watts at 1g/w you should get roughly 600gs we will say.
Then you made your switch. Now you use 300 watts, and get 1.2g/w which should get you roughly 360gs.
So maybe you don't need the extra weed which is fine and maybe you don't flip any to make up the extra money I get it I'm not trying to be a dick here. I just personally thought the math was interesting on your statement. You seem very happy with the switch so that's all that matters. Heck maybe you even used the extra 300 watts to set up another tent, and then your yields actually went up, which would be what I would do. I wouldn't care about the $130 a year in electric savings if I could increase yield by 2x for the same wattage over more area.
That's what really draws me to LED, the vastly superior canopy coverage. And now a days with the level LED tech is at, they even have enough umph to penetrate the canopy well
. I'm really looking forward to making the switch in my garden.