Dying Back items
Even the wing back items could use a dye channel. The white wings could have the feathers always blend into a white tip, while the black ones blend into a black tip. Though this change would be especially important for glider + back piece combinations that have a dyable glider.
There are even gemshop back pieces that I didn’t buy for the sole reason that they don’t fit my character’s colour palette. Adding one or multiply dye channels to these backpieces would increase their compatibility with existing characters and their colour palettes tremendously.