Don't get me wrong, I have seen some impressive results from closet LED grows. But to spend $25k-$30k to replace HID's is not worth it IMO. Looks good GroErr. LED's have their application, but their initial capital cost makes them prohibitive for most who grow for production.
Itsme.
They out-perform any form of hid/hps from a production standpoint watt-for-watt, just a higher
up-front cost. It depends on how you look at it. Smaller grows are easier to get into from a capital standpoint, like I'm only running 600w over 3.5 x 7' or so. But the same logic applies to larger ops.
If I were starting up a large op I'd still go with the COBs or newer QB boards after seeing what they can do. That run I posted above pulled ~1.3 gpw with 9 strains/12 phenos/13 plants in 1, 2 & 3 gal pots. Not exactly a setup for yield. If I were to take my better producers and fill that same footprint I'd be hitting 1.7-1.9 gpw easy at 30w/sq./ft. HID or hps can't touch those numbers at that wattage, many are running 50+w/sq./ft.
So if you take the reduced wattage at say 60%, then factor in lower costs to manage the environment, the payback is there in a few runs, everything after that is gravy. If you had the cash to swap watt-for-watt, the same payback applies, just in increased production vs. operational savings, even faster payback.
My main driver is quality and I haven't seen or smoked anything close to the quality I'm getting now with any form of hid/hps, or even CMH which I ran for the last couple of years. Cheers.