Ran across this thread on the ATAG forums; the attached mission file is a very good tool for evaluating how good your visibility is, although bear in mind that every server has a RCU file that governs dot visibility, so results may or may not be the same offline as online.
I'm going back and testing with SweetFX for this. As you has said, turning the in game AA off does help a bit. But I really don't want to run with no AA. SweetFX actually has a nice SMAA that works well in place of the game's system that doesn't hurt dots quite as much. I'm just trying to redo my sharpness filter to work with the game's AA turned off. Not thrilled with anything yet.
I think the biggest problem here is that you really can't "tune" your settings while online, which is where it counts, and here again, it's the fact that a server's RCU file may differ from server to server. You just don't know.
The more I'm messing with the sharpen filter, it seems there are more trade-offs than better or worse. I can get a setting that brings out a dot a bit more, but when it's a closing bandit at maybe 1-1.5km, the same settings helps mask it compared to default. It just seems to depend on if it's a dot, or a tiny airplane (like 5 pixels), against the sky vs against the ground/water.
The lack of pre-rendered AA from the game does slightly hurt the shape of distant planes for ID purposes. You lose some of the simulated detail of tapered and curved edges that distinguish the planes. So again, a trade-off for having slightly darker distant dots. Not sure if it's worth it yet.