I think I'm kidding myself that I can put 600w inches above a meter. Any petiole the light touches is sprayed red, while the tops of buds can refuse to go any higher. I can combat the red with crazy amounts of Mg but then I get Mg patterns on the lower leaves that are hard grainy brown. I can't balance it.
In fairness I come from GreenPower son's at 1.7umol/j that would of put maybe 1.5umol/j down on a good day(shade and age losses). The 301H is talking 3umol/j so 400w is a third more. I'm trying for double. It was never a great idea. Though a 450w run did come in 25% under target so I'm reluctant to try that again. Though I recognise I'm doing this wrong.
450w has always seemed perky. An improvement over 400w that can be seen in a day. Beyond 450 I can't say I have seen any improvement at all. Keeping in mind it's not 18" up, it's more like 8 but spread
My lights are the R-spec blend and the sodiums were top notch in award winning shades (50p shades. Pro ultra something. 8 sides..)