Ummm, DIY! But seriously, that article was funny. I stopped at that BS about 'current reduction' vs 'pwm' because anyone that knows anything about LEDs knows that PWM is MUCH more damaging to LEDs because you are constantly turning them off/on to create the desired brightness, it just turns off many times a second so our eyes don't notice the flicker. LEDs have the same faults as an incandescent bulb in that respect, you can only turn them off/on so many times before they fry, where as running them at a lower current but within proper forward voltage via 10v manual dimming will not cause excess heat or damage to a properly built LED fixture, key word, properly. The only way a 'current reduction' method would damage LEDs is it you are using the wrong drivers (constant voltage instead of constant current) or very mismatched LEDs. LEDs are actually MORE efficient running in the 500-700mA current range than they are running at full current (1000mA-1500mA), the lumens per watt is much higher at the lower currents. If one uses cheap chinese LEDs that have a wide range of specifications for forward voltages and you put them all in the same series of LEDs, some of them will be driven slightly harder than they should be. Easy solution, always use quality LEDs (Cree, OSRAM, Philips), and always use quality drivers (Meanwell). On top of that, always by the same BIN LEDs and put those in the same series, so one 'channel' is all cool whites, one is all royal blues, one is violet, one is cyan, one is red, etc, that way you will never run into the problem described in the article regarding mismatched LEDs.
Kessils are fantastic lights, but I would never recommend them for a 6' tank. You would need a few dozen to cover a 6' tank adequately.
As for cost, here's one for you. I spent $1000 building 2 LED fixtures 6 years ago, one for my 60G, one for my 75G, in those 6 years I have had maybe 6 LEDs burn out and need replacement, and since it was DIY, it took me all of 60 seconds to replace and $3ea for the LEDs, FAR FAR cheaper than having to replace T5s or MH. In those 6 years, if I add up bulb replacement cost that I was spending annually ($320), plus electricity savings $28,000+ in 6 years, it really is a no brainer which lighting technology is superior.
Today the light I made for my 60G that cost about $400 6 years ago can be made for under $150, and use much more efficient LEDs than I am using (Cree XR-E). I have never had a fan go bad, but I made sure to buy the correct type for mounting horizontal, spent $20 per fan, but if one did die, $20 for a fan from newegg and 2 minutes of work to replace it. The fans are dead quite, loudest part of my tank is the slight gurgling on the overflow pipe. On my 75G light I have my fans on a PWM controller with the LEDs, and on a temp controller, so the fans are either off or spin very slowly (140mm fans) when the temp of the heatsink exceeds 90f, well below operating specs of the LEDs. Money I have spent replacing blown LEDs over 6 years, ~$20, less than the price of 1 T5 bulb.