I will start this out by saying this is my first lightsaber, ever, so please, anyone correct me if I am wrong here :).
In my case, I got the RGB option. I have 3 LEDs - 1 Red, 1 Green and 1 Blue. I can change the intensity of each LED by selecting a value from 0 to 1023 for each in the override.txt file. I have settings for the 10 colors and their 10 corresponding FOC colors. For each, I select the R,G,B intensities. For example, I could have a pure red blade color 1023,0,0 (no green or blue, just red at full intensity). It's FOC is bright white 1023,1023,1023 (full intensity of all three colors).
If I just received the suncrusher single colors, I would still have 3 LEDs but it would be a little different - 2 Colored LEDs and 1 White. The colored LEDs can be BOTH red, blue or green if you chose those 'simple' colors (simple meaning non-mixed). That is why for those 'simple' colors, people say they are brighter than the RGB sabers on red, blue and green. If you chose orange, for example, it would be 1 red, 1 green and 1 white. Purple would be 1 red, 1 blue and 1 white. In the case of orange and purple, there is no benefit to brightness over the RGB option.
In the single color sabers, the white LED is turned on for FOC. Using a similar example above, a pure red blade color setting (drive) would look like this 1023,1023,0. It's FOC (fdrive) would be 1023,1023,1023. In this case, 2 red LEDs are at full intensity all the time and then the white LED is turned on full intensity for the FOC.
Again, I am new to all of this, but that is how I believe it works. There is another thread called 'Lock up effect question' started by pfek on the 9th asking how to turn down the intensity of the FOC on his suncrusher green saber. Luminara informed them to try making their third value 800 instead of 1023 to tone down the intensity of the white.
Hope that helps and please, if I am wrong, correct me :). I want this to be a place people can go to really understand the color options available and how to do them without the trial and error and with the correct information.