Ok, as promised, spectral pics!
First of all, to highlight what exactly the difference is, ReefBreeders replaced 2 of the Indigo 440nm LEDs with another 3.5k and 5.5k white one. This is ultimately the only difference between the 2. This first pic is both fixtures, each with only the 1st channel running at 100% to highlight that. 5.5k on the left and 440nm on the right. No lens filters were used on these first 2 pics.
This is with all channels at 100%. It isn't as obvious with the camera looking much bluer than it does in person, but the left side looks much whiter in person and is just that perfect daylight look.
This is what the tank looks like with all 4 fixtures running, on schedule, with a 20,000k filter. This is pretty close to what it looks like to the eye in person, just a hair bluer.
All in all, not an extreme difference, but enough that it pulls that nice daylight look and most important, makes me smile :)