Ive wondered the same thing about spectrum shifts. I have had a set of leds up and running for about 6 years. Sold them and that guy has been running them for about 2 years now. Only thing that has needed replacing was one of the 48 leds, and a power supply.
With DIYs my corals always had a slight hue of green. Now with kessils I'm seeing colors closer to t5s. My diys were about 96 leds on 48" long tank. Leds were 48 mixed blues, 4 reds, 4 green, 8 uv, 8 cyan, 24 mixxed whites warm and neutral.
So my setup was Blues were Crees, all others were bridglux. Not sure about color shift, but I did notice that all the leds had shifted to what looked like white/clear. When turned on they still displayed the correct color to my eyes.