I agree. The teras would just end up being very expensive feeder fish.
When I got my exodons, one of the staff at the FS threw a rosy red in the tank to show me how mean they were. It wasn't pretty. after about 30 seconds, the rosy was dead, had its eyes ripped out, and was being carried around the tank by the neck by the largest exodon. These guys absolutely require a species tank, and even then (if kept in small numbers) they are likely to turn on the weakest members of the shoal.