Figured I'd throw my voice in this thread as well. My boyfriend and I play side by side. The lag is very noticeable when watching movements on his computer versus movements on my computer.

We have managed to down Titan HM with our FC, but it wasn't smooth, people did sometimes get hit by the Weight attack, and it took us a while, even with someone calling out in mumble what the next attack would be.

I would agree with many that downing Titan is possible, but you have to rely on predicting when he'll cast attacks. We haven't started raiding yet, but I really don't look forward to wiping on a boss fight several times to learn an attack pattern because we can't rely on the visual cues the game provides.

I'd also note that we have raided in other games (WoW, SWTOR, Tera), without any sort of issues. We know how to move out of stuff, clearly we can predict stuff if we -have- to. The problem is that we shouldn't have to resort to that.