I dunno about Fixed Edition, but XInput Fix 2.0 by SonicFreak works wonders with 360 controllers. It doesn't have support for DInput, though, but it has configurable deadzones. SonicFreak has a post about it if anyone's curious. Just look up SonicFreak XInput fix 2.0
If I remember correctly, the Steam version doesn't have DInput support, but to my knowledge, the Steam version is complete ass anyways.
For reference, SADX PC (not Steam), has some weird crap with the deadzones of XINput controllers as well as thinking the triggers are always set to a value of -1, which essentially forces the camera to spin in Free Camera. It also does something weird with the right stick and causes the game to go to the closer look mode in Auto Camera if you're standing still. This ultimately affects the way the camera moves in Auto Camera while the character is moving in-game, and never in a good way.
As for Steam, I have no idea how controller support works for it because I've never had it nor played it, and I don't care to, but I've heard that it's literal ass, so eh