That would require the
feature matrix script to consider experimental builds, too (also 70D & co.). Features available only in some experimental build could be marked with a different symbol (icon proposal welcome), and the tool tip could indicate the name of the branch(es) that cover(s) that feature.
Is this something you or anyone else can help with?
The script uses Python + some shell scripting, and can be tested on your local machine (output is a static HTML page; you may need to get some CSS files from the website to get correct formatting).