As I said, use as little as possible and is a good thing XIM team give us more settings to have the chance to combat or remove aim assist on games that doesn't even have that option.
Yes, there is inherit and unavailable small acceleration and having a subtle slow down on the aim assist bubble compensates not having perfect tracking without acceleration and turn limits. But the slow down must be very very subtle IMO to get in and out of the hit-box target easier and lead shoots, I'm not saying that you should go AA OFF in all games, most has horrible aim/look, not XIM fault.
Unfortunately, and as
OBsIV mention in other post, lately game developers have a trend were are cutting down quality ports and aim behavior, making it hard to XIM to perform at its best.
About bad lag compensation and aim assist hurting is fact, games like COD and BF the majority of guns are hitscans based less prone to have issues, but in-games with different approach (projectile) where bullet travel is significant, like Overwatch (Hanzo, Genj, Widow), Battlefront, PUBG, Fortnite.
This can be an big issue if the game netcode has poor sync and very strong aim assist that pulls you to aim to a spot were a hundred of ms before was a hitbox, this pull doesn't allows you to catch up the target movement. Battlefront II is one of the worst I have seen, follow by Fortnite.
Hitbox was out of bounds on this one, even though he made it:
There is a bunch of videos like these.
This
video explains in depth this problem.
So yeah it depends on the game and its implementation, projectile, bad server sync, strong aim assist.
I guess this dreadful mix might be the culprit behind on many ST remakes requests.
I think XIM dev team are devoted on deliver the best precision on consoles, where aim assist is not in the picture. I can not say anything on CoD , but on Battlefield they certainly deliver.