Sorry SE, but endgame won't work if you don't fix something.

[AunaYuuki]

Most of the people here saying they don't have issues play DD characters as mains. They don't realize the problem mainly resolves in healers/blm/sch/smn because their casting times.

Things that work or have been working:

Melee/upclose party (don't have a video yet. Tested it and it works with a smart party who can move fast close together) : everyone can stack behind titan so all the plumes overlap into 1. Easier to dodge just strife left or right.

Ranged DD pt SPREAD OUT. http://www.youtube.com/watch?v=Pz4Vp8VhJfA

Do not cast a long cast spell between landslide and plume stages. Use Swiftcast if needed.

Don't cast anything if plumes show up under you. Instead move outside and cast something even if you interrupt it. (Been said a few times here)
I hope this helps out a little bit. SE knows there are still issues with Titan Hard and server sync. Friends of mine have sent tickets in and got basic replies that they are working on it.

People saying that these people just "suck." Didn't play beta to even know this issue has been going on since then. It kind of reminds me of Ifrit extreme in 1.0 but they never fixed that.