I too am replacing 1000w DE fixtures with a 630w Fixture, both from
nanolux. I cover a 4x4 with them; and I'm seeing improvements in the way I can run my CGE environment. Temperature control is easier to obtain, and plant surfaces have cooled down 10 deg F by infrared measurement. Side by side, I saw sick plants under HPS and healthy plants under CMH; all variables the same including soil, genetics and training/grow style. And you'd be a fool if you didn't notice the quality increase on the CMH; but the best part was going down 700w in power consumption and getting higher yields. I swapped out the HPS mid grow after seeing premature yellowing and lower growth rates; and the plants responded by greening up and growing faster.
I can see a place for HPS lights, but for me I am seeing increased quality and yields with LEC.