i think there are quite some syncro bugs going on.

Like for example, if i would run behind a running mob i don't hit it but would still get global cooldown and the animation. Or the known "bug" or "lag" as some may call it when there is a aoe circle for example, you get out like 0.5 second or 1 seconds before it ended, you still receive damage.
Both of these bugs are extremly devastating for melees. Especially the first one as you cannot dps while running unless you're literally inside the mobs model.

Other than that. There is a bug where i, as a MNK do for example a Bootshine to switch into the Raptor form. I know for 100% i hit it. But sometimes it takes 3-4 seconds for me to be able to do a Twin Snake or True Strike cause it's still greyed out.

PS: If some do not believe me it's that brutal. I thought so too until i did 3-4 times Stone Vigil. The endboss has alot of AOE. You will notice that he will smack you even though you're out. Which is as you can imagine kinda anoying.

There does appear to be some form of lag and for me it's positional as well. And i mean your position vs the targets position. I've had this happen quite a few times where i stand right in front of a target, facing the target and try to use any offensive ability. All i get is a message saying you can't use this ability, target out of range or whatever. Some of these targets i follow when they move and after i while i can use my offensive abilities. At other times i just give up and move on to another target. Also running after a target during a fate for example can at times be difficult to use an offensive ability as well. Or the ability is used but it has no effect. The last i always just assumed i missed. But now i've my doubts.

I've not seen any rubberbanding. Although i have seen a few people running erratically in which i'm pretty sure their connection was their problem. I have a 50mb/s connection and it's performance right now is stellar in games, etc.