I have fun doing it. When I was 18 and getting back into the hobby I really wanted gen 1 radions but couldn't afford them, so I taught myself how to build LED fixtures. I'm now 23 and have gotten pretty handy at it. Both fixtures are controllable from my phone. I could have cleaned up the sunpower retrofit by not mounting the power supply on top of the fixture but I got lazy and didn't want to make the extension cords that would be needed to run it elsewhere and out of sight. I personally don't really care that its mounted on top but I'm sure some people would.
My display tank is the one with the 4 bulb t5 hybrid and I built that LED fixture 3.5 years ago and its still running strong. Building it is nice because I don't have to deal with warranties and crap. I just fix it myself and usually runs me $20-$30 to fix it. The only issue I had was when I switched to screen tops and took my glass tops off. I have 8 wrasses so sometimes they splash and one little droplet of saltwater managed to somehow reach one of my drivers on my display tanks lights, but it was a $25 fix so no biggie. I try to build them to last and so far its doing very well. I'm tempted to re build my DT lights just because my inner nerd wants to test out all the new LEDs that have come out since I built it.
I'm not finished with the sunpower hybrid yet, I plan to add 2 more color channels into the mix. Its not needed but I want to try out some new LED's that I may incorporate into my future builds if I like the results. I have a par meter and the sunpower put 125-150 par on the sandbed of my frag tank when using 4 t5 bulbs, after the retrofit I did it puts just a little over 500 par on the sand bed (I of course have it tuned back). My display tank lights I need to check again because I forgot the par numbers.
The specs for the sunpower is pretty simple, 28 royal blues and 14 neutral whites. I plan to add 6 cree deep blues and 6 luxeon lime leds just to test them out. The LED fixture over my DT has 28 royal blues, 14 neutral whites, 20 hyper violets/uv, 8 reds, 8 greens, 8 cyan's, and 8 true blue cools. Its not to shabby for being built almost 4 years ago.