The funniest thing to us COB LED converts is when someone uses the electric bill to justify/indict the decision to switch. Why, you might ask?
COB LED runs cooler, saving both on power bills and helping to improve the quality of the product. Running cooler also saves on HVAC investment, maintenance and especially operating costs.
Better spectrum helps vigor, health, growth, terpenes and makes them look darn nice in the grow. Seriously.
No bulb replacement. Again, look past the basic costs of the biannual ritual of bulb replacement to realize that lumen/PAR depreciation doesn't just happen at the end of this interval, BOTH spectrum AND PAR/Watt efficiency suffer the effects of aging cumulatively, starting the very first time the lamp is struck. In other words, the only time the lamp actually delivers its rated output is during your very first day cycle. It's alllllllllll downhill from there. How much do you think a cumulative 15% less light costs YOU in terms of yield?
Then, there's the maintenance labor aspect itself; replacing bulbs is a bitch. And even dangerous, depending on where those lamps are and whether any get dropped.
Dropped HID?! INSTANT HAZMAT SITE! EVERY HID has mercury in it, so if you smash one, you've just coated the whole area in mercury dust- or vapor if it was running. Mercury very bad, just saying.
Power problems? COB LED don't care. But HID lamps must have a cooling off period, almost none of them will hot restrike.
So yeah, you'll save some on your power bill- but those savings will be dwarfed by the combination of even larger savings outlined above and in increased yields and quality.
I predict that in 5 years, only die hard Luddites will be clinging to their light bulbs, and they'll be finding lamp replacements to be a daunting challenge. This trend will be accelerated by the public perception of the indoor grow industry's wasteful habits, power company's desires to reduce demand and general environmentalism.