Well, the patent shows CD-4 being used for Cyan and Magenta, but I was told it was CD-3 in K-14. Now, I am confused as well. CD-3 and CD-6 generally yield dyes with better dye stability and better hue for viewing with the human eye. That is why CD-6 was chosen and why I believe that CD-3 is used in the other two developers.
CD-6 was planned for use in the generation of color paper after Ektacolor 70 paper (Ektaprint 3 process in 1969) and in Ektachrome E-6. However, Kodak was sued by Berkey, Pavelle and GAF for coming out with the Ektaprint 3 process and plans for the upgrade to CD-6 were cancelled.
If plans had continued, there is a good chance that RA4 and E6 would be run with CD-6 with even better dye hue and even better image stabilty. You can thank those that sued Kodak, making management nervous about changing processes for this.