The defective auton doesn't need any beefing. It's already potentially deadly depending on your weapons loadout and piloting skill. I'd personally remove it though and make autons identified on sight. Since they have different masses it's just a gotcha for new players.
I'd like to see a standoff auton with a flenser or ballista. I'd like to see an auton with a couple DM1500s that would self destruct when it ran out of missiles. And a military version with a pair of NM900s.