Niko, if you get The Fiji Purple and balance the light with green so its viewable, is that slot you used up for balance worth it ? In the example case of a 2 bulb fixture vs 4 bulb etc ?
If I understand you correctly you are asking if adding green light to please the human eye is also useful in some way to the plants.
If this is so then I think that the "middle" part of the spectrum (the one that makes the color of the light pleasing to the eye) is not completely useless for the plants. Look at all these graphs for the wavelengths that are best for photosyntesis. They all differ a little from each other. But what is pretty obvious is that between the high blue and red spikes there is also some activity. Meaning that the green light will actually be beneficial to some degree.