So I've been toying around with some people's theories on chocobo dyeing and I fully support the:

Apple +R -G -B
Pear -R +G -B
Berries -R -G +B

Plum -R +G +B
Valfruit +R -G +B
Pineapple +R +G -B

I've also realized one VERY important detail while dyeing my own chocobo. I think whatever color you give them FIRST directly impacts what color they change to the most.

Another post I read mentioned something about Primary and Secondary colors and I think that's a whole lot of true.

I fed my chocobo 1 berry > 1 apple and 4 pears from Plum Purple, had NO messages and he did not change color this morning. I then fed him the EXACT same fruit this morning in a different order: 4 pear > 1 berry > 1 apple and got feather changing messages EACH time I fed him.

This is all just my observations of course!