Just did this on Sunday and went 9/10.
Our set up was 3xRng/nin, 1xThf/nin, Blm, and Rdm or Whm (We had 7 people).
The Blm would run in and Elemental Seal Sleep ga the worm right in front of Flayer. The Thief was spamming acid bolts and the Rangers were going nuts. Whm or Rdm would help cure the DDs when shadows went down and would keep Barstonera up, Blm kept Sleeping and helped heal. Once Flayer was down we backed up to the ramp and killed the worms one by one. Overage time was 15 minutes. Maybe the old style of 6 Blm Ga-ing them still works but this is a certain win. 3 of the fights we lost 1 of the Rng from draw-in Stonega II since the back worms would not be asleep and we still had no trouble finishing this fight in 20 minutes with only 5.
Our one wipe came when the Blm had a problem with a macro and cast sleep instead of sleepga and us silly Rangers ran in to kill Flayer only to get Stonega'd to about 25% health. Blm got drawn in as he tried to cast Devine Seal + Curaga and was killed. It was only a matter of time then.