While those red and green LED's may be 'useless' from a growing coral standpoint, they aren't useless from color rendering standpoint. A lot of higher end fixtures have started moving towards a 'full spectrum' or 'colored' approach for LED fixtures and adding in colors such as red, green, cyan, 'UV' and even amber or orange. They do this to help with color rendition in coral and fish.
Obviously, if your DIY setup was made in such a way that LED's can be swapped out, by all means play around with the led composition until you get a color that YOU are happy with (that's the only opinion that matters at the end of the day anyway)