There is currently no difference between Masterwork Armor and Dwarven Quality Armor.
They both get +1 armor AC.
This is not the same with Masterwork Weapons and Dwarven Quality Weapons.
Masterwork weapons get +1 AB, while dwarven quality weapons all get +2 damage of their main damage type.
As it is, it's pointless to have two different drop types which both do the exact same thing.
I think, in order to differentiate the armor types, perhaps Dwarven Quality armor could mirror it's weapon equivalent and give 2/- DR or maybe even just 1/- DR vs slashing (which is a desirable damage type to be resistant to). This would make DQA desirable over masterwork and possibly even crafted armors until better crafted gear can be acquired.
It would still be full weight and have no other benefits, but could fulfill a role of greater durability if using an alternate form of armor AC (mage armor, varnish, magic vestment, etc)
I'm putting this here because I'm not sure if it belongs in the item requests thread