The main problems I have seen with LED lights are this.
Marketing- Too many people believe what they read immediately. Led lights can provide more of the spectrum the plants actually use and need as opposed to bombarding them with a full spectrum light. Yeah that's true they can if they were made by a combined effort of botanist and lighting manufacturer. In which case I'm sure many are not.
If you are selling something you don't need to care about anything except selling it...It doesn't need to work. Some people care some people do not.
I have not yet had a great deal of time to invest researching LED lighting effeciency yet but I will be working to build my own since the price of 1w 50000 hour light emmiting diodes are purchasable with pennies in comparison to buying a 300-400 diode setup for the price of a NICE car.....
Another main concern I would have when purchasing a LED setup is that if each light in the fixture is just RED (650nm) and BLUE(450nm) waves then I forsee an immediate problem where are the RED(649nm) and BLUE(452nm) Waves coming from? OR since I am a human and with out a spectrometer I will see no difference between 460 NM and 450 NM lightwaves, they will look blue to me eitheway.
(Speculation) As a lighting manufacturer I may be able to produce lighting arrays much cheaper by only focusing on 2 wavelengths and then paying my marketting division to do it's job by claiming I use a better spectrum than competitors when clearly I do not.
(Fact) Thylakoids in chlorophyl are aggitated by more than just 2 specific wavelengths of light. There are also two(discovered) photosystems which carry on seperate processes one requiring <680nm and the other taking in 700nm wavelength light. Which means more energy production when shot with a range of light than just by a wavelength. Which is probably why HID lighting works the way it does, Yeah it shoots a shit ton of light at the plant that the plant doesn't care about it. But it isn't limiting the plant down to only 2 wavelengths of light that it needs or doesn't need for that mater depending on who you buy from.
I have read many many reports thusfar in the begining of my research to suggest that most people who have had bad LED lighting experiences are just victims of good marketing.