Here is my take:
Aquarium leds started becoming popular a few years ago and the first fixtures were all white leds and they worked... sort of, for some, but they really weren't very good and they were crazy expensive.
Then somebody realized that coral zoanthealia use more of the blue spectrum and fixtures started coming out with white & blue leds. Better than the just white, so early adopters sold their all whites to people who didn't know any better and bought the new white & blue fixtures. But there were still serious issues and good fixtures were still crazy expensive (which made it easy to sell off used leds). Corals were doing better, but a lot of people were killing corals with good fixtures that were too strong (bleaching/sunburn). Other people were having issues with cheap fixtures that were too small or too weak. So leds start to get a bad reputation, but they did work OK for some people.
Then dimmers got added and led fixtures improved. Not nearly as much bleaching. PAR meters started becoming popular and more common. More people were successful. But junk fixtures were still common and quality fixtures were still expensive and led's reputation didn't improve much. Some early adopters were mad. They had killed corals and paid lots of money for led fixtures they weren't happy with.
Then 'full spectrum' fixtures came out. They used several different blue & white leds along with UV, violet, red and even green. Now the fixtures were really pretty good at growing coral and safer and easier to use. They were still pretty expensive, but some good fixtures were coming out at somewhat lower prices. Older, led fixtures were still being sold used and even more people were getting screwed by fixtures that didn't work as well as the newer ones. And cheap junk led fixtures were still being sold, even by big companies with good reputations like Marineland. So led's reputation was still struggling to improve.
Now China has jumped into the market with both feet. Some of their early fixtures were just more junk. And some people hate them just because they are from China. But a couple of companies in China have been making good quality fixtures (maybe not Eco Tech, AI or Maxspect quality, but still good quality). And they have brought the price of a good quality led fixture down to the range of other forms of lighting like metal halides and even t5 fluorescents. But other Chinese and US companies continue to make and sell junk. So led's reputation is still struggling to improve. Many early adopters who were burned now hate leds, or at the very least, don't trust them. And they have good reason to feel that way. They got burned early on and there is still a lot of trash led fixtures being sold.
So do today's leds work? Heck yes! They grow corals just fine, they run very cool, they are more efficient and you don't replace bulbs every 9-18 months. I was a solid MH & t5 user until the end of 2012. I went to MACNA and saw lots of high quality, expensive and marginally expensive led fixtures. Then I learned about EverGrow in the Chinese led thread in this forum. I don't care where they are made. Heck, half the stuff we buy in the US is made in China, whether by US companies, Japanese companies, South Korean companies or Chinese companies. But EverGrow and Twilight seem to be making an effort to build and service better quality led fixtures. So a lot of new, lower end buyers are getting leds now. It's opened up a new market segment. But there are still less useful, older led fixtures being sold in the used market and there are still lots of new junk fixtures being sold as well. Some people buy the junk, get burned and say leds aren't any good. Others have bought better and newer and are having great success.
Over the past year I've owned and recommend Eco Tech Radions (still expensive though), OceanRevive (a new US company), EverGrow (Chinese) and Reef Breeders (but I think most or all of their fixtures are made by EverGrow). I've owned and DON'T recommend Marineland, SunSun and TaoTronics. I've never owned AI, Maxspect, BuildMyLED, Twilight or Kessil, but by reputation, I suspect they are good quality. I'm sure there are others as well, but those names just came to mind first. My first rule for buying an led fixture is, if you don't recognize the name of the company, don't buy it! At least not until you find out what their reputation is... or who makes them for that company. There are lots of brand names out there who don't make their own leds.
The pic also shows something that seems to be common with led's, the tips look great but the branches and base usually have a different appearance, so instead of a solid color, it is great where recent growth is and average on the older parts of the coral. While I do not want to get into a led versus traditional light debate, it is very common to see corals that exhibit that partial color tendency under led's. Of course there are tanks under led's that don't exhibit it, but they are very rare on these forums.
