I'm honestly willing to try any setup that we agree may work best. I'm serious about these missions, so completion >>> gil + xp, lol.
As for possible setups, I'm with Elvi on this one. Poor Elvi was Stunned most of the time against Omega, which caused two problems: 1. massive cure dumps from the mages and 2. inability to keep hate tool rotations going. In retrospect, the only damage I took was from that AOE Hyper Pulse (I think) that went through shadows. Granted, it was a lot of damage, but I think the majority of our mp went towards keeping Elvi up and running. NIN tank would alleviate that A LOT.
I hear from most that a NIN with bat earrings can go Ichi > Ichi, which makes dealing with Stuns more of a non-issue.
If I go as BST, here is my thought: Cati can go as THF for Mammets. A BST with an HQ jug will do more DoT than most other jobs at that level. I doubt the Mammets will be able to take out my jug in the first part. If I can keep my pet alive, it will be healed to full when we move to Omega, and my Call Beast timer will be ready. That gives me two full jugs against Omega. I fear that 3 AOEs or so will wipe out my pet, so hopefully I can squeeze out some decent damage before they are toast. Regardless, I know we will be fighting Omega long enough to allow me to call a third jug before we finish him off. Hopefully it's still alive when we beat him, cause it will be healed to full, giving me another freeby for Ultima. I think BST COULD work, but keep in mind it will put me in AOE range, so I wouldn't suggest this if we stick with PLD tank.
My recommendation for our next try would be:
Elvi NIN/WAR, Cati THF/NIN, Nekio BST/NIN, Ash BLM/WHM, Boots RDM/WHM, Soph WHM/?
If Cati has marksmanship levelled, she can do what I did... it seemed to work pretty well. If nothing else, as THF I tried to spam bolts from melee range, dumping SA or TA+WS as I could, and running out of melee range to recast shadows after Hyper Pulse, and get some cures, all while spamming bolts. Daggers were doing around 10-20 dmg each, and bolts were doing 25-40 or so, with poison effect.