This script by Luca Scheller generates a vertex paint layer which is based on the polygon size, similar to Substance's influence map.
The add-on offers the ability to create a vertex paint layer with the color value based on the size of the respective polygon face. It also offers the ability to convert a vertex paint layer to a vertex weight/group layer. The Add-on controls/options are explained in the YouTube video below.
- New Features -> Check out the BlenderArtists thread for more information.
Here is a video demo of what the add-on can do: