I'm currently running head to head comparisons of COB LED and HID lighting.
I'm running 5400W, total wattage ballasts included, of 860W CDM Allstart lamps on magnetic ballasts, perhaps not the very latest in HID tech but solid in terms of spectrum response. This lights a rack of 144 sq ft.
I'm also running 5400W of Cree CXB3590 3500K CD BIN 72V chips at 54W each. This also lights a 144sq ft rack.
Early results show that the LED light source is so much more powerful than the HID that the plants were shocked when they went into bloom. They had problems the first three weeks of bloom and some never recovered.
That said, my average yields still went up. I had a new personal best; one plant hit 32oz, up from a previous best of 26oz.
Quality is obviously better; tighter, denser, heavier nugs with more frost. No one disagrees with the assessment that it's also more potent.
COB LED is better. It's better than blurple LED panels as well; in head to head tests, my CXB powered modules drastically outperformed them, growing healthier plants at similar rates with less than half the watts used and heat generated.
From this perspective, all the complaints about COB LED lacking UV light smack of sour grapes; grow a crop under them and then tell me they need more frost, lol
I'd say HID lighting is for streetlights but my city is replacing them with... yep, you guessed it- COB LED! Light bulbs are sooooo twentieth century. If you're still growing under HID, it's time to join the new Millennium.
At this point, it's no longer a question of whether LED is better, it's more a discussion of how the new tech can be most effectively and efficiently deployed.
Just so the purists can't cry foul, I'm also testing a new 1000W class low frequency square wave ballast and I'll be running an 860W CDM Allstart lamp on it. We'll see if the improved performance of this combo will keep it competitive with COB LED.