I emailed the guy in regard to this and thought i would post his response for info purposes, i havent got the knowledge on LED's like some of you guys have so here is what he said,
UV is generally included for several reasons. On the practical side they are included for the reason that the 2 blue absorbtion peaks where photosynthesis is most efficient occur at 453nm and 430nm, and normal blue and royal blue leds put out 465-485nm and 450-465nm. This means that although its possible to hit the hit the first peak (just), you cant hit the second peak with (most) royal blues. Because of this alot of lights use UV. UV lights are actually a bit short wave (390nm) to hit the second peak, but the peak does extend back down below 400nm, althought at a reduced efficiancy.
Another reason given for UV is it repels/kills insects and kills mould/fungus. UV actually atracts bugs as they see by it! Its like a big 'come here' sign which is why bug zappers use it to attract bugs! Not something you want on your plants! Anything strong enough in UV to kill fungus/insects would kill the plant - and you!
Instead of UV, I use very short wave blue leds, and I am now using 2 different wavelength bins of Royal Blue, instead of blue and royal blue.
Far red 740nm is claimed to encourage flowering. My lights do have a small
amount of this from the warm white leds, but they also have alot off
660nm far red. 660nm changes a specific chemical which is associated
with flowering and absorbs at 660nm to a different form which absorbs
720nm light. This form then either decomposes back to the 660nm form
naturally when the plant is in darkness, or when it is hit by 720nm
light. There is no diffinative study which shows 720nm light has any
reall effect on flowering, but lots that show 660nm does.
Possibly the best thing I can do is post some output and wavelength specs for my leds. These show I aint joking when I say my lights are the best. Basically all marketing and product placement is niches. I make the best lights, and use the best leds available because that is my niche. If I could make a better light possibly using better/more expensive leds I would do do, and would simply charge a bit more. These are the sort of lights you would have if your best mate or brother was a very good engineer and superb craftsman with lots of money and decided to make them for you as a birthday present!
Here is some info on the led's used in my main 280 watt light
Actual best
absorbtion
wavelength / My Leds / Lumens or Rradiometric Power
439 nm / 430 - 440nm / 870 - 1030mw
453 nm / 445 - 450 / 870 - 1030mw
642nm / 620 - 630 (standard red - very efficient) / 107 - 113.65 lm
662nm / 650 - 670nm / 550 - 710mw
Warm White Cree XP-R / not applicable / 160 lm