Ok, CD-3 and CD-4 are not interchangable. The dye hue shifts due to polarity and the activity differences will cause problems.
And, you cannot take a developer designed for Br/I emulsions and make it into a developer for Cl/Br emulsions. You must remove ingredients, but you can take a developer for Cl/Br emulsions and change it into one for Br/I emulsions by addition of ingredients.
I not work with CD 4. I thing those is not dramatic changes by replacing CD 4 with CD 3 in color negative processing.
I use for all photo color negative films ECN II process (without prebath). The results are always good. Even with expired film. http://www.apug.org/forums/members/g...421-catei.html
For me it is easier to use ECN II process for color negatives - photos.
For color slides, I use the CD 2 in color developer. Not CD 3 color developer. http://www.apug.org/forums/members/g...422-scala.html
I have found it fairly simple to mix ECN-2 developer (somewhat simplified, there was a formula posted here). I have not made darkroom prints because of the contrast issues, but if you want to scan to print digitally, I can think of nothing better. Kodak Vision 3 250D is awesome -- it's impossible to lose shadow or highlight detail. I've tried to upload an example, to see what you all think.