ILLUMINATOR UFO TRI-SPECTRUM FIVE BAND 90 WATT LED GROW LIGHT
About LED lighting:
LED lighting is the newest technology to hit the market. LEDs are notoriously efficient, and this 90W light uses 90 individual LEDs to reportedly achieve the same grow-output as a 400W HPS/MH system. They are lightweight, portable, efficient, and give off less heat than their HID counterparts. Best of all, the bulbs tend to last MUCH longer and you can go many years without having to replace them. I used it to extend my growing season since I started my seeds very late and wanted to finish them without risking a frost. I was able to get beautiful flowering results from all of my plants, and the fruit continued or increased developing on all of them that were in good proximity to the light (in a 2-3' [60-90cm] diameter light footprint).
It's important to note that while the light is much more efficient than the HID lights, it does not give off more lumens. This is because an LED light is only capable of giving off one wavelength of light, unlike all other lights that give off a range of wavelengths. As a result, combining different LED colors can target specific photosynthetic pigments and give only wavelengths that the plants will use rather than flooding them with a lot of unnecessary green and yellow light. Plants use mainly red, orange, blue, and violet light to produce energy, so white light wastes a lot of power on wavelengths that the plants don't use. This is why plants appear green; they 'spit back' the green and yellow light that they aren't using!
Pros:
-Uses almost no electricity. At 16 hrs/day that's only 43.2 kW/hrs each month vs nearly 200 with a 400W HID
-No need to replace bulbs for MUCH longer (I've heard 80,000 hours)
-Easy to install, very portable
-Gives off almost no heat, unlikely to burn your plants from being too close
-No ballast to worry about
-Can use through entire grow cycle
Cons:
-Be wary of imitations! Lots of Chinese fakes are known to exist
-There seem to be many that fail partially or completely in the first month.
-May need to add additional heat to the room in winter
-Pricey (90W lights run around $250-300 in the US, unsure about UK)
-Smallish grow radius
-Need to turn off light to observe plants
What I saw:
When I brought my plants under the light I noticed an immediate explosion of growth. My Tabasco started growing much faster, and my Bhut Jolokia flattened its leaves and basked in the new lighting (I don't think it liked it outside for some reason). Fruiting continued if not increased, and the plants loved it.
My most aggressive-growing plant was a Charleston Hot. It drank double the water of all the other plants, ate triple the fertilizer, and loved light. Unfortunately I let him drift a bit outside of the growing radius and he browned/yellowed in a few weeks and started to die. I had a total of five fruiting plants under the lights at this time, so I reduced it to four and the rest seemed to be doing fine. Make sure that you don't save too many plants for this light! Four plants should grow alright, but this is not really meant for high-volume use. You can probably use it for the first month or two of growth for a good number of plants, but don't expect to get a lot of fruiting plants with this one. I am still trying to figure out the flower-dropping on my Bhut Jolokia under this guy, but I am 90% sure that it's not a lighting problem. Also remember to get your plants right under the light and keep the light ~30cm (or less) from the tops of the plants if they are fruiting.
The heat output is very low, and there are even three fans built into the tiny round light. This is nice and the fans are no more irritating than a noisy computer. My plants have shown no signs of any sort of light burn, even quite close to the unit. I haven't had any problems with the cold yet, but I'd imagine if the room gets particularly cool in the winter additional heat should be added to the room. You can't rely on this light to warm your plants!
Recently I noticed that about a dozen of the LEDs aren't lighting up and I contacted the manufacturer for a replacement. Oddly enough, they seem evenly spaced, so it could have been one color that went out. I will keep you updated on that. It seems that this is a frequent problem, and some lights even have one power unit go out inside them which can cause most of the LEDs to go out. I'm not sure if they are burned out/faulty LEDs or if it's a different problem. Unlike HID lights, LEDs are very numerous, so the circuitry involved in building them is more complex and more likely to break down.
**Update: After I contacted the manufacturer they informed me that these in fact were the 16 infa-red LEDs that are used for a better wavelength span. They are invisible to the human eye.
The light is very blinding if you are observing your plants when it is on. Not only is it very bright, but the deep pink color isn't exactly pleasant on the retinas. Whenever I look at my plants I have to turn it off or only observe for a few short moments. I wouldn't recommend putting this in a room where you are in frequently unless you can put some sort of shield between you and your plants. It's meant for them, not you!
Overall, I was very pleased with the results. In the long run, the LED lighting saves big bucks on power and can grow plants quite well. I would recommend it highly if you're looking for a new grow light. Fatalii from fatalii.net uses this same grow light when he needs to boost his plants without inflating his power bill. It also uses no mercury and is rather 'green' I suppose

Here's a shot of one of my plants about a week after getting put under the new light. The fruiting and flowering absolutely EXPLODED when it got the new rig, and it was using good ol' outdoor sunlight before that!
My Tabascos fruiting beautifully under their new light:

I'll answer any questions to the best of my ability. This is the first major grow light I've owned so I can't really compare much to HID results. I also haven't tried seedlings under this light yet, but will be starting some soon and will keep you guys posted!
-Matt