I've done this twice in Trials Roulette, once as PLD and the other as WAR. (I liked it more as PLD but we cleared faster when I was WAR and felt squishier, both times I was getting adds to the middle)

Honestly once someone says "ok x and y you handle cannons and snares. All other DPS stay on vishap. Healers/others who aren't melee stay in front of/middle of the pack. Who got giant killer? Remember 1st one doesn't need snares, just hit it when his target is over the red circle. Others need both snares."

... it's been 1-2 pulls for me. @_@;