BTW, in case anyone was interested: I created a demolition crew of drones and let them dismantle a building.
It worked reasonably well, except for some reason the drones decided to just run out of compressed air instead of returning to the charging station. Maybe it was too far away?
I recommend arming them with good tools. Ideally I'd ensure they broke blocks depending on which tool they have (so that axe-wielders killed book-cases, etc) but have no idea how to go about that.
edit: can they wield multiple tools? I didn't test that. Maybe they can hold both axe and pickaxe, that would make things go a ton faster.