i was told that armours dont drop dura. never notice any dura drop on my steel armour but i have seen others (with rarer armours) complain they are dropping lots.
also you might want to rember, if you repair something and its at 40/65 it doesnt really make the dura drop quicker. hard to put into words but it doesnt work the way many people think it does (same as standing in the drop zone you idiots :P)