The extra damage probably helps keep threat a bit better although it would get a tad expensive after a while I imagine. In most cases if the DPS in the group are a tad overzealous, tell them to ease up a bit or maybe get a BoSalv if you are lucky enough to have a paladin. Another thing that makes Engineers a bit better at threat is the lovely Tank goggles. All I can say is my felsteel helm crys in the shower being compared to that haha. With monster Sta/defense/HIT/dodge, they are some very primo loot.