If I had any sway with the fine programmers at Toon Boom, Harmony would have following additional features:
- It’s own internal 3d render engine… or support for Blender3D in place of Maya.
- Perspective guides like Sketchbook Pro or, preferably, Krita https://www.youtube.com/watch?v=FG7ODi3Z204
- Inbetweening like Cacani
- Animated brushes like Krita https://www.youtube.com/watch?v=Rs1Iw7LIuKU