This new panel is an experimentation and I hope you’ll find it useful.
It is inspired by the excellent Flash extension “SmartMouth” created by http://www.ajarproductions.com/pages/products/smartmouth/
Here the link to download some characters to test my extension: http://cartoonsolutions.com/
The concept here is to draw all your character expressions in a single PSD which is embedded like a Smart Object in a master PSD. Then the panel allow you to switch the visibility of the layers inside the Smart Object (in fact a copy).
If you are on Photoshop CC 2015, here a custom installer: