So i have been using the Kessils since April. I got two of them over a 90 gallon, so 340L or so.
I can't comment much on energy consumption as i live in an apt. complex with centralized utility billing, but I do save a small fortune in bulbs. I used to have two 150w MH's over this tank. Are the kessils a real switch out....i am not entirely convinced.
Look shimmer effect is great, you get good plant growth, and yes they do mimic natural light and you get more shadows like you naturally would. I do find the light to be a bit dim at times. I could try put another kessil over the tank, but a 90 really isn't designed for that with the central bracing and its not a small chunk of change for another one.
If you look at the 120 gallon that they put a link up for...i mean it has 4 Kessils, that's approx $1200 in lighting at retail cost here in the U.S including the goosenecks, and if its a true MH replacement, putting 4 150w MH's over a 120gallon is a pretty significant amount of light.
I have no idea what these cost in SA. As an ex-Zimbabwean i can only imagine they cost an arm and a leg. I don't know if there's anyone over there who has a tank with them - if you can find someone - i'd go check them out first in person.
I'm a medical student moving onto residency in a few months, and my plan is to get a 180 gallon when i move. Realistically what I'll do is likely get another kessil, however, look into some alternatives to supplement it like the Ray2 strips or something.
I'll try attach some pics here. Excuse the fact that the tank is not exactly well scaped, lack of hardscape, etc. Like i said, I'm moving soon, and so I'm just fiddling around getting things to grow, playing with ferts, etc. I will say that my tank does get some supplemental sunlight from the window now that its winter, and it makes a fairly big difference on pearling.