If everything's going right the defensive cooldowns usually arn't used except for soloing, so there's no reason to not just set IR/Fracture/Bloodbath/Mercy Stroke/Second Wind. I don't see any reason for opinions on Mercy Stroke to be divided because it's off the global cooldown, so you'll get bonus damage if you use it right which is always good. Fracture on the other hand, has caused many a flame war on boards. Personally whenever I play DRG I almost never touch Fracture anymore, when you consider that you'll usually be capping accuracy the amount of damage it does is only a smidgeon higher than your basic combo, and one small screwup makes it not worth it at all. I'd still have it set if you have absolutely nothing else to do (not like there's anything else to equip), but DRG's combos are pretty long so it should be on the bottom of your priorities.
Also, yeah, as Chronix said, MNK was already top melee DPS (and if we're talking single target they were just plain the best DPS). The amount of buffs they got just makes them undisputed #1, the only reason not to fill your party with good MNKs for DPS is because of that inane "your LB fills slower" penalty to any party with more than 1 of the same job. Really dumb way of "balancing" the game by just forcing job variety on everyone.