The diodes HLG uses on there Quantum Boards are one of the most efficient on the market. Samsung does make one that is better but its not available yet.
I built my own from scratch and you have more experience then I do. here is my build. Its a clone of there HLG 550 light.
BUD LIGHT The Quantum Board Build
You can build this yourself, you are more than qualified
You may have to go with the QB288 boards and different drivers. but you should have a 500 watt light that works as good as a 1000w hps single ended light
Hope that helps 