Agree with a lot of things mentioned on the thread and will add my two cents:
I was well into the hobby when T5 lights first came onto the scene, and CLEARLY remember when numerous people online at sites such as reef central told me that T5 would simply NOT grow coral, yada yada yada... well guess that advice didn't work out for them
Bring us to present day and I see a lot of the same arguments now with LED, people claim that now LED just can't do it long term, don't bring out as nice of colors etc basically using the same arguments that people told me when I got my first TEK T5 lighting system many years ago. I think new equipment just needs to be proved
In my opinion I totally agree with several above who have mentioned most LED failures can be attributed to user error. I see far to many folks wanting led, but unfortunately they go cheap eBay route etc instead of quality proven units, and honestly you just will never know the long term quality when you buy cheap units (my opinion). They may be built with cheaper components and thus may end up losing spectrum intensity or power over time, thus leading one to believe that they won't work long term.
Now if you look at some of the more "higher end" types of LED lighting, I think the problem here is 2 fold:
1. Most people don't know what they are doing with all the "controllability" ... i.e. they constantly mess with lights, or simply set lights for what they think looks cool, rather than focusing on par and spectrum of light. I also believe that many people are so focused with getting as high of par levels as possible that they really miss out on the fact that most* corals will be totally fine with par values around 200-300. Seems like everyone wants that LED that cranks out 999+ par levels, and they simply end up frying corals in the process of trying to get increased growth (more is not always better) and get upset with LED.
2. This is just opinion after owning every type of lighting from high end LED, T5, halides, PC, and the old school T8 bulbs.... I personally think people don't use ENOUGH MODULES over their tanks for LED. I realize manufactures show charts of par values etc of the led covering like say 18 " etc, but personally feel that by adding more total number of LED lights (gets expensive quickly obviously) many would see much better results. My opinions on this have been through observation after using AI sol, hydra, and now 52 HD (as far as LED lights are concerned). Through my course of LED i have noticed that when I add more total light modules then recommended, I see MUCH IMPROVED results in my reef. I attribute this to having more total # pucks above the tank, thus helping to eliminate shading. I think just because par can reach out to acceptable levels of 18" doesn't necessarily mean you are getting adequate light spectrum out around this areas. Also you may have to have the lights cranked up all the way to get adequate par at 18", but this means that area directly under the pucks could be well over 400 par etc.... thus creating to much variation in the tank. By adding more units above the tank, you increase number of pucks thereby increasing the number of total light sources. This not only keeps par and spectrum more consistent throughout the tank (much like T5 do) but also allows you to run lights at a lower percentage as well.
Personally I didn't upgrade to LED to "save money" as by purchasing what I feel is an adequate number of LED units, I actually have spent more than a T5 or halide unit.... I upgraded to save from having to order replacement bulbs several times a year. I just don't want to depend on having to order bulbs, and then dispose of old bulbs, and store replacement bulbs etc.... it is far easier for me to buy a quality built LED until, and not worry about bulbs for a good 4 years or more.
So in conclusion while user error def plays into LED failure, I think too many people don't utilize enough actual light modules over their tanks, and thus as coral begin to grow they end up getting shaded, either physically shaded or possibly spectrum drop off due to the beam-like nature of LED lights. More pucks to me will just lead to better overall spectrum spread, leading to more "consistent" results. But again this is all personal, time will tell
