The following musings began as a simple post on 3reef and ended up being quite long. However, I think the info is valuable to anyone in the market for LED lighting.
There is much, much more that goes into an LED unit besides the diodes used. Top quality emitters can be used, but if you have supbar electronics, drivers, etc on the inside, then you have a subpar light. Sure, the diode might be rated to last 50k hours with a 30% output loss over that period, but what if the drivers used are only rated for 10k hours (plus, what are the specs of said driver: is it constant-current, constant voltage, what is the tolerance, variance range, etc?).
Just because you have a spectrograph for a particular emitter doesn't mean that range is actually being emitted. What a diode produces depends entirely on the power being received, which depends entirely on...you guessed it...the quality of the power supply and drivers! So, just because you are buying a fixture with the latest-and-greatest insert-fad-diode-here, (a debatable subject all on its own) if you don't know what's attached to it, you have no idea if it's actually producing the spectral curve it's advertised to produce! This is all aside from the fact that the spectral curve of the vast majority of emitters leaves a lot to be desired...
I repeat: there is much, much more to LED lights than there are to the relatively simplistic fluorescent and MH fixtures we're all used to, and at the moment, unfortunately, you practically have to be an amateur electronics guru AND a lighting guru to be able to make effective comparisons in this (temporarily) flooded market.
Most LED fixtures contain mediocre internal electronics. Why is this? Both for cost savings and because manufacturers know that the vast majority of consumers know nothing about the workings of LED lighting, and those that are not as ignorant concentrate solely on the type of diode being used without realizing that the other associated electronics have a large impact on the light emitted.
Over the next 2-4 years there is likely going to be a serious market contraction as most of the internal electronics of most LED fixtures will begin to fail. A few brands will begin to become the norm in each price point, and consumers won't have to spend days researching electronics AND lighting to be able to make a decision on what to purchase. Right now is a tough time to be looking for LEDs, because the average consumer simply doesn't know enough to make a comparison, and really, they shouldn't have to. The LED market hasn't reached the point where the average consumer has a good idea as to what they are purchasing, however. For a market contraction to occur, consumers will have to stop buying the bad products, and this process will take a few years.
All I can recommend in the meantime is to purchase from companies that offer as much info about their product as possible. The more info they're willing to offer about every aspect of the light (and the longer the warranty - ever wondered why most LED products are warranted for 1 year, when they're advertised to last for 10? The *diode* can *potentially* emit for 10 years, but what about everything else?), the higher the likelihood they produce a quality product.
I wouldn't purchase a light if the manufacturer did not provide a spectrograph of the actual light (not just the diode) and brand of drivers being used, as well whether or not the driver is constant-current or constant-voltage. I'm probably pickier than most (as these requirements drastically limit the number of fixtures I'd consider spending money on, down to probably two or three), but I advise others to begin to demand more info, lest we be stuck with inferior products in a field that offers so much potential.
