Rapid LED Onyx light. Priced right and state of the art. See my review under Dynamic Aquarium.
I disagree with your point of view on the price. It maybe has the quality like AI Sol, but I will need to point out few things that concerns me.
1) I don't see any info on if the light is dimmable or not, not on your post, nor on their site. I would say the light is not dimmable. You can't really find a fixture that doesn't offer dimming options, to have one that can't be dimmed cost over $270 is very very expensive. That being said, if the light can out perform other fixture, I would say $270 for a 6" fixture is still fine. That lead to my second concern.
2) It said on the site the fixture is similar to AI Sol, however, AI Sol is consuming 75W power and onyx consume 90W. That alone tells us it is not efficient as AI, you got more LEDs, running higher power and yet only running at similar light output as AI sol.
3) Base on your PAR reading that compare to the Taotronic:
"Under the middle of the fixture:
750 at the surface
300-400 midway
200-250 at the bottom (18" deep)"
First, you are comparing CREE with Bridgelux or even EPISTAR, for those read a lot about LEDs would know CREE is always approx. 25% more powerful(efficient) than bridgelux and could be even more than EPISTAR or any other brand.
To compare to the fixture, here is a PAR reading for a 90W "Taotronic" unit with CREE @ 3 and half " above water level.
3" 3000(Off the chart so the meter not able to give me the true reading)
6" 2047 (9")
12" 753 (15")
24" 316 (27")
32" 230 (35")
36" 200 (39")
(*) is how far it is from the fixture.
So the PAR you got was 12" AWL
So at 30" it is 200-250 that is about 35 to 40" range PAR reading for the 90W "Taotronic"
To give you an idea on that fixture pricing, it is about $336 with dimming and timer or $399 with controller that can do cloudy and lunar cycle and built-in timer.
4)
UV ( anything less than 400nm) is great, but violet/purple are overrated. It doesn't worth the extra $30 to $50 more just because the fixture has "violet"
To back up what I said, you can easily compare a fixture that has no Violet/purple/UV LED diodes like AI SOL White spectrum graph.
AI Sol - Performance
VS
Something has 405nm (by far the closest to true UV in the market) like the Ecotec Radion
Radion ™ XR30w Pro | EcoTech Marine
You can see the actual spike below 400nm almost identical, it contain almost the same amount of spectrum around 390nm. The only thing that actually is different is the spike around 405nm range (simply they added that specific spectrum LED in there)
I am only trying to point out the facts why I think Onyx is actually way over priced with ok performance and no dimming. All data taken are from 3rd party site like AI and ecotec. The only piece data is taken by me is the PAR reading I took with apogee 200 PAR meter. If you find any of my point is not true, you are welcome to speak out as I am willing to listen to others opinion.