1.) I do that for sparks, stripping off enough MAB/Mdmg gear to hit around 500 each nuke on whatever I'm on and then spamming if for objectives, is efficient.

2.) AoE damage output is a factor for how efficient your job is at cleaving, but not the only one. Blu/Blm/Rdm are all quite good at it, and reasonably close, is my point, so it's silly arguing that one has a big advantage over another, some are better in some locations, but all are close enough in Exp(orwhatever)/Hour overall that it's kinda a wash.