There's a lot to learn about LEDs. It is not as simple as HPS, bulb plus socket, plus ballast, and reflector.... I'm sure you know this, LEDs run on multiple smaller diodes. Some 120 degree angles lenses, some 90 degree angles lenses, some 60 and 45 degree angles lenses. Then some 1 watt, some 2 watt, some 3 watt. And some even 5 watt... Whatever...
The higher the watt individual diode, the better the penetration. And more importantly, the narrower the lens angle of each diode, the better the penetration. 60 degree penetrates really well (that's what she said). Anything more, you're just spreading your light out too much. It's like trying to spread an HPS out too much. Like 400 watt HPS for a 12 x 12 room. You wont get results...
Anyway, there's a lot of shady LED companies out there. Hydrogrow LED.... Cammie MnKenzie, their owner? Used to be Cameron Scott Wieldraayer, a race car parts salesman before the sex change, (s)he did this because (s)he was dodging the law and those he ripped off. "Mike " from Grow Led Hydro, is also known as Irishboy, a "3rd party" grower doing "grow journals" for "Mike". Promoting his own products... Then there is the Chinese knockoffs... And the insane claims, 90 watts equal 400 watts HID. My fatass it equals that much...
Long story short, I am an HPS user, as well LED. I have dealt with the LED lies, I have spent lots of money on many LED false promises. And have dealt with less than acceptable yields with them... Currently, I am running 3 different LEDs and 1 HPS (400 watt). 2 of the 3 LEDs perform slightly better than CFLs (HTG and Blackstar), and the 3rd, not sure the name brand, I got it used, watt for watt, it performs better than my 400 watt HPS. For larger grows, I cannot see why multiple panels of the same light cannot be possible to cover a larger area. I use 3 to cover a good portion of my grow area. The same can be applied for even bigger areas.
I do agree though, LEDs are expensive. And it is hard to find a good one. Unlike HPS. How long does it take to find a good HPS setup for the un-knowledged? Fast. How long does it take to find a good LED? I speak from experience, a long fucking time. I spent a lot of money, wasted a lot of time, but kept looking, and found good LEDs, though expensive, they perform well.
This is the way I see it: If you are able to manage the heat, HPS is a great option. I've used 400s and 600s, I was happy with them. LED is good if you can not deal with large amounts of heat, but will cost more up front. A lot more. I enjoy my LEDs, they are great in the summer time, it is hot where I live... I like HPS in the winter and cooler months out of the year.
I also agree, LEDs do better with shorter plants than taller plants, but also, each lighting method calls for different growing situations... There are many different growing styles, match your growing style up with your lighting method, and do it right, you'll get the most out of what you're doing.
I'm bored of LED vs. HPS forum arguments, I use both lights, and like both lights. I have stated my opinion of them, and at this time in my life, I choose to use both LED, and HPS in my garden. I get practical results with both.
I think watt for watt LED may be able to match HID if the plants are kept short. This, though, would be where the high cost consideration would come into play for me. I don't think that saving just my cooling costs would justify the high initial costs. The bulb cost is also an issue, but since I started using Digilux's, my yearly bulb cost has been drastically reduced. After 6 months running 12/12 I've lost less than 5% lumens. To offset the high initial purchase price, the LED really needs to save some electricity. I've crunched the numbers, and around 2/3's is the cuttoff point for me at todays prices. In other words, I would need a 650-700watt LED do the same job as a 1000 HID. Also, the penetration issue has to be improved to be usefull in my garden. As a legal med op, I have a limitted plant count. Ideally, no more than 32 plants in every 8x8 tray lit by 4 - 1000 watt HPS's. With that density, my plants need to finish at 36" tall with dense marketable buds down to within 6" of the top of the rockwool block. My HID's give me quite a few 1 gram very dense buds 6" above the rockwool...that's 4.5 feet from the bulb. These plants yield 3 ozs each...all of which are perfect market buds due to carefull pruning at week 2.
My needs are probably more demanding than most. Because of this, I think LED's are still quite a ways off from being a viable alternative for my grow op. But, it does seem that with recent advances in the technology (much of which is simply higher wattage lights), LED's will be showing up in more and more closet and single tray grows.