A few builds ago i found that if aimed correctly you could use the number 5 ability for staff guardians (And sanctuary) to move any friendly NPC or vendor.
They only move a small amount at a time but if you do it for a long time (or have friends help you as i did) you can move them quite rapidly about.
i did find however that if you pushed certain NPCs to far they would run back to where they spawned and no, you cannot push NPCs off the edge of cliffs or to steep rocks ect.
^ should be a screen shot of the Rank 10 glory vendor which myself and a friend moved to the rank 20.
The key to doing this correctly is to aim about half of the arrow in the ground targeting inside the NPC and cast it, it will push them in the direction opposite from yourself