Most efficient way to move Goblinite down many z-levels?

Solution 1:

Dig a new 1x1 shaft all the way down from the surface, with a hatch cover; then designate a dump zone next to the shaft and mark all the goblinite for dumping. You can drop a crystal flute a hundred z-levels and it will be none the worse for wear. Just make sure to build that hatch, as the goblins may not survive the journey, but a giant eagle will. If you do this, make sure the shaft ends away from a route dwarves are likely to take, preferably in a 1x1 room behind a door, and make sure you don't unforbid the dumped items before the last one has landed, you don't want your haulers' brains to be introduced to high-velocity copper swords.

Having that equipment gathered inside bins in a stockpile and then having another stockpile take these bins is the second best option (you'll need to remove the take designation until the stockpile is full of binned items, though), but it is still significantly slower and requires more effort than just bulk dump designations. Running minecart tracks between the two stockpiles might save you a lot of dwarf-hours, but will cost quite a bit in man-hours due to having to build tracks on every z level separately.

Solution 2:

Build the 1x1 shaft and then set up a minecart stop next to it that dumps on arrival into the shaft. At the bottom of the shaft, say zmany+1, build a hatch cover and link it to a lever.

Set up the rest of the minecart route to take from a weapons/armor metal only stockpile you make (it can be pretty small) and then get it all working right. The wiki can help you with minecart routes, they're weird. Your dwarves should pick up the goblinite, put it in a stockpile, then put it in the cart and push it to the shaft, where the cart empties into the shaft. Cart returns, refills, repeats.

At the bottom when you want to get stuff out, toggle the lever, take a beat for stuff to fall down, toggle again. This way your dwarves are never exposed to high-velocity metals, and if you put an appropriate 1x1 stockpile under the goblinite chute you can even link that stockpile directly to your smelters.

The whole system should run without your intervention, so you don't have to mark to dump and then reclaim stuff later. Yu will have to tweak the lever now and again, unless you feel clever and hook it up to a slow repeater .