Currently, there is 0 benefit from having Armstech on a main character, from a self-use perspective. There is nothing to learn which provides comparable bonuses to operation weapons, no improved barrels to outfit the barrel-less weapons found there. Yes, they are adding barrel slots to operation weapons in the future, but this does not mean that Armstech will provide a benefit unless more is added.
From a profiteering stand point, I make more money from selling diplomacy materials on the market than I do from selling companion weapons or the occasional level 50 custom weapons.
Please buff this crew skill, or I'll be forced to switch to Armormech for the augmented Rakata offset or Biochem for its obvious (even after this latest nerf in the patch notes) benefits in order to optimize my character, because there are certainly no benefits to being Armstech on a main character as it stands.