When I was
playtesting Swatters in 28mm earlier this year I used my facehuggers and chestbursters as Swarms and cheap toy maggots and ants as Drones. Swarms are scarier than Drones so it seemed appropriate, plus I didnt have appropriate painted swarm models to hand.
The drones are individually rubbish. They definitely have uses and are used as sentry types in some of the scenarios so its a good idea to have a few, but even in a large group they dont feel as scary as a large group of face huggers should. Which is why I used facehuggers as swarms, which are a bit more dangerous, rather than speed bumps, if you know what I mean.
So I reckon that the drones should be the equivalent of bug civilians, not really designed for aggression. Probably not as dangerous as a pack of face-huggers.
A crappy phone photo to illustrate the route that I took for drones:

It will be interesting to see what you Khurasan guys come up with
