I'm sure there are more than a few of us who have been waiting out the twelve month exclusivity window to pick up this game, but when the various bundles dropped on Steam I found it all rather confusing, especially which combinations include the early-access masks and shaders. For those who are wondering the same, I put the question to the reps on the Illfonic forums and got a response:
https://forum.predator.illfonic.com/t/steam-bundle-confusion/21087 (https://forum.predator.illfonic.com/t/steam-bundle-confusion/21087)
Long story short, despite giving no indication on the listing itself, the Predator Bundle Edition does include the extra content at an overall discount of 15%, so it's definitely the version to go for if you're after that DLC.