Ingame Antialiasing has to be set to NONE for SweetFX to work.
Also, increasing any of the two "HDR" values above 1.0 results in artifacts on ingame UI elements such as squad icons or the minimap.
As AA is a no-go, you can employ "Downsampling":
According to my local tests, using 2560x1440 on a 1920x1080 display actually results in a BETTER graphical result and FAR better perfomance than the ingame engine AA. So: Get it, do it! It's easy and stuff will look super awesome again.