I found it was an absolute crapshoot trying to work out which to get - I'm a big fan of blue lights, but man it seems hard to get a consistent shot of each under the same conditions. I ended up ordering the 10000ks since the usual consensus seemed to be that they were typically more blue than shown in most shots.
Then I look at the shots from Steely up there, and the 15000ks look great. But then I went back to the original video that helped me decide -
http://youtu.be/-EyabHl1dPA
and the 15ks there look extremely blue - almost like a 50/50 blue/actinic. And the 20000ks are almost a pure actinic look on their shots.
But yeah for me the best in that video seems to be the 10000k/15000k mix (if only they made a 12500k light). I figure I'll see if the 10000ks work out and then order some 15000ks later - or maybe see what happens with the A350.
Rather than a full review - just some things I didn't see mentioned very much when I read up on them. I got the 10k/sky blues.
The good:
* Fantastic colour mixing - just a small slightly monochrome ring around the edge of the light at long viewing distances.
* Small lens size and wide spread means you can place them so that no light hits a brace or strap of glass.
* Incredibly intense light from a small package (and a small space behind a small lens in a small package, even) - just amazing. Objects like fish cast a single clear shadow. The only LED caustics ("shimmer") that truly resemble a MH light that I've ever seen.
* A very crisp blue-white colour that seems much more like water at shallow depth than the usual "resembles incandescent" or "resembles office fluorescents" warm/cool whites LEDs.
* Light pretty much goes where you want it, not in your eyes/wall/canopy. Unless you're looking right up into the unit from significantly below it, there's no blinding eye strain and very little spill-over of light.
The bad (only deducting half a point though):
* 1 of 3 units has a faint whine in the fan - still very quiet but annoying if you're close. Other two are almost inaudibly quiet unless you put your ear to them.
* Mounting options, if you don't get the goosenecks, are pretty awful. Kessil need to ship the unit with more backplate templates. At the least, they would ship hanging attachments significantly taller than the existing ones. Stock mounting options just don't match the build quality of the rest of the unit at all.
* Could have used a secondary lens of some sort, existing ~100 optics don't let you tilt the unit without a lot of reflections. Spread is quite wide (24" diameter circle at 8" from the diffuser).
* Breakaway cable could use more overlap between connectors.
So: very happy with them overall with some minor nuisances.
Also, for Aussies - ordering from marine depot went fine, and they only need an ordinary kettle/pc power plug.