I don't see why this feature requires a Navi-based GPU to function on DX9. I mean it works for everyone on DX11, but DX9 is reserved for Navi.
Navi uses a different (newer) implementation of DX9 - and Anti-Lag was first integrated there. It will be integrated into the legacy DX9 soon...
How do you know it will come to legacy DX9? Has that been confirmed, or are you just guessing? I'd love to use it in Rocket League since I cap my game at 140fps.
so it's not really for you then if your doing over 100fps it's designed for those getting between 60~100fps so it feels like your playing at much higher refresh rates / Fps but aren't able to get up there