After watching from the sidelines for nearly a year, I think it is time to try the Substratum theme engine. Quick take, it is fun, but do take care with Notification settings!
Substratum places an overlay over the icons, menus, notifications and quick settings. When it works you get icons in the color of the theme, or black background. When it doesn’t work, you get icons with a solid blot of color or unreadable notifications.