People's hair is their second face.
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By the way is that the new body with the old hairs? I'll admit she looks great like this... funny how much it helps, I mean I'll still miss the old Yoon face, but just returning her hair back to what they were would likely help people accept the change.
I mean you might have had some good reason for changing the hair, maybe overall the new appearance fitted your mental image of Yoon better, but without you stating things clearly its likely to leave some people unsatisfied due to the shock of the change.
I mean at least Sienna is Sienna not Jasmine, which might create some bother as it mean the other character is gone, however at least it doesn't impede on our mental image we had of the character as its effectively a new one. Yoon however, had a fairly established image for any of the per-existing players so yea, it would be shocking, but if that is what you believe Yoon should truly look like, than keep the new appearance.
Also if you do retcon the reboot and return to the old version, nothing needs to be lost, you can reuse this character for a new character, same for Sienna & Cherilyn. Its the good part of the fact you are dealing with a in-development process, is that you can change and adapt things to your liking.