my record is 23 wins, 5 losses, for BCNM40 giddeus. 3 of the losses were my 3 first tries; the other two were flukes like the brd or the healer(s) getting disconnected. so i'll address some concerns:
1. for a non-bst PT, the most important member is the brd.
2. the second-most important member is the healer, whether this be a rdm or whm.
3. once that core is formed, all you need are damage dealers. pld adds safety but takes away killing power.
4. flood is quite easy to handle. read below.
my best PT for this was BRD, RDM, RNG, RNG, DRG, DRK. we buffed before entering the burning circle; the RDM was around 60 so buffing beforehand allows him to use the higher level spells. the BRD and i (DRK) ate fish mithkabobs, RDM ate apple pie +1, everyone else ate meat mithkabobs. we moved up to the walkway, used the short-timer buffs, then i ran in first and voked the dvorovoi (black mandora). brd was right behind me and slept all the mandoras. once brd had hate for all the white mandoras, i pulled the black one away, to the far end of the arena. when flood begins, i stun and weapon bash then run to the entrance of the burning circle, while the brd uses foe lullaby and the other mage uses elemental seal + silence. using this method, no one has ever been hit by flood, even if flood is the first thing the black mandora uses. the damage dealers go nuts, and we kill the white mandoras one at a time. once you get it down, it's very, very easy. with that PT, my record time was around 12 minutes, average time was 13-15 minutes. with a PT of BRD, WHM, BLM, MNK, DRK, PLD, our time averaged 22-28 minutes depending on if anything went wrong, if anyone died, etc.
if you have 40 seals and you need a PT, send a POL msg to me, and i can try to set you up with a PT. just let me know time available, job lvl, amount of seals, and if you have any other PT members already.